Test Bank for Physics Principles with Applications 7th Edition by Giancoli – Test Bank |

chapter 6

Exam

Name___________________________________

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the

following statements is correct?

A) Both do positive work, but person X does twice the work of person Y.

B) Both do zero work.

C) Both do positive work, but person X does one-half the work of person Y.

D) Both do positive work, but person X does four times the work of person Y.

E) Both do the same amount of positive work.

1)

2) Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving.

Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on

the car.

A) Joel does 25% more work than Jerry.

B) Joel does 50% more work than Jerry.

C) Jerry does 50% more work than Joel.

D) Joel does 75% more work than Jerry.

E) Neither of them does any work.

2)

3) If the force on an object is in the negative direction, the work it does on the object must be

A) positive.

B) negative.

C) The work could be either positive or negative, depending on the direction the object moves.

3)

4) A 35-N bucket of water is lifted vertically 3.0 m and then returned to its original position. How

much work did gravity do on the bucket during this process?

A) 180 J B) 45 J C) 0 J D) 90 J E) 900 J

4)

5) You throw a baseball straight up. Compare the sign of the work done by gravity while the ball

goes up with the sign of the work done by gravity while it goes down.

A) The work is negative on the way up and positive on the way down.

B) The work is negative on the way up and on the way down because gravity is always

downward.

C) The work is positive on the way up and negative on the way down.

D) The work is positive on the way up and positive on the way down.

5)

6) Which one has larger kinetic energy: a 500-kg object moving at 40 m/s or a 1000-kg object moving

at 20 m/s?

A) The 1000-kg object

B) The 500-kg object

C) Both have the same kinetic energy.

6)

7) A truck has four times the mass of a car and is moving with twice the speed of the car. If Kt and Kc

refer to the kinetic energies of truck and car respectively, it is correct to say that

A) Kt =

12

Kc. B) Kt = 2Kc. C) Kt = 16Kc. D) Kt = Kc. E) Kt = 4Kc.

7)

1

8) Three cars (car F, car G, and car H) are moving with the same speed and slam on their brakes. The

most massive car is car F, and the least massive is car H. If the tires of all three cars have identical

coefficients of kinetic friction with the road surface, which car travels the longest distance to skid to

a stop?

A) They all travel the same distance in stopping.

B) Car G

C) Car F

D) Car H

8)

9) Three cars (car L, car M, and car N) are moving with the same speed and slam on their brakes. The

most massive car is car L, and the least massive is car N. If the tires of all three cars have identical

coefficients of kinetic friction with the road surface, for which car is the amount of work done by

friction in stopping it the greatest?

A) The amount of work done by friction is the same for all cars.

B) Car N

C) Car M

D) Car L

9)

10) A 4.0 kg object is moving with speed 2.0 m/s. A 1.0 kg object is moving with speed 4.0 m/s. Both

objects encounter the same constant braking force, and are brought to rest. Which object travels

the greater distance before stopping?

A) the 1.0 kg object

B) the 4.0 kg object

C) Both objects travel the same distance.

D) It cannot be determined from the information given.

10)

11) You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road.

If you had been traveling twice as fast, what distance would the car have skidded, under the same

conditions?

A) It would have skidded twice as far.

B) It would have skidded 1.4 times farther.

C) It would have skidded 4 times farther.

D) It would have skidded one half as far.

E) It is impossible to tell from the information given.

11)

12) Which requires more work, increasing a car’s speed from 0 mph to 30 mph or from 50 mph to 60

mph?

A) 50 mph to 60 mph

B) 0 mph to 30 mph

C) It is the same in both cases.

12)

13) A stone is held at a height h above the ground. A second stone with four times the mass of the first

one is held at the same height. The gravitational potential energy of the second stone compared to

that of the first stone is

A) one-fourth as much.

B) four times as much.

C) twice as much.

D) one-half as much.

E) the same.

13)

2

14) You and your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your

friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do

so. Compare the gravitational potential energy of you and your friend, after you both reach the

top.

A) It is impossible to tell, since the times you both took are unknown.

B) Both of you have the same amount of gravitational potential energy at the top.

C) Your friend’s gravitational potential energy is greater than yours, because he got to the top

faster.

D) It is impossible to tell, since the distances you both traveled are unknown.

E) Your gravitational potential energy is greater than that of your friend, because you traveled a

greater distance in getting to the top.

14)

15) The graphs shown show the magnitude F of the force exerted by a spring as a function of the

distance x the spring has been stretched. For which one of the graphs does the spring obey Hooke’s

law?

A) Graph a B) Graph b C) Graph c D) Graph d E) Graph e

15)

16) A heavy dart and a light dart are launched horizontally on a frictionless table by identical ideal

springs. Both springs were initially compressed by the same amount. Which of the following

statements about these darts are correct? (There could be more than one correct choice.)

A) The lighter dart leaves the spring moving faster than the heavy dart.

B) Both darts had the same initial elastic potential energy.

C) Both darts move free of the spring with the same speed.

D) The heavy dart had more initial elastic potential energy than the light dart.

E) The darts both have the same kinetic energy just as they move free of the spring.

16)

17) When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no

air resistance. At what speed should you throw it up vertically so it will go twice as high?

A) 2V B) 4V C) 16V D) 8V E) 2V

17)

3

18) When you drop a pebble from height H, it reaches the ground with speed V if there is no air

resistance. From what height should you drop it so it will reach the ground with twice speed?

A) 2H B) 2H C) 16H D) 8H E) 4H

18)

19) When you drop a pebble from height H, it reaches the ground with kinetic energy K if there is no

air resistance. From what height should you drop it so it will reach the ground with twice as much

kinetic energy?

A) 2H B) 2H C) 16H D) 8H E) 4H

19)

20) Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If

there is no air resistance, when they hit the ground

A) both will have the same kinetic energy.

B) the heavier one will have half the kinetic energy of the lighter one.

C) the heavier one will have four times the kinetic energy of the lighter one.

D) the heavier one will have twice the kinetic energy of the lighter one.

E) the heavier one will have one-fourth the kinetic energy of the lighter one.

20)

21) Swimmers at a water park have a choice of two frictionless water slides, as shown in the figure.

Although both slides drop over the same height h, slide 1 is straight while slide 2 is curved,

dropping quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the

bottom of slide 1 compare with v2, the speed of a swimmer reaching the end of slide 2?

A) v1 < v2

B) v1 > v2

C) v1 = v2

D) The heavier swimmer will have a greater speed than the lighter swimmer, no matter which

slide he uses.

E) No simple relationship exists between v1 and v2.

21)

22) Two frisky otters slide down frictionless hillsides of the same height but different slopes. The slope

of the hill of otter 1 is 30Â°, while the slope of the hill of otter 2 is 60Â°. If both start from rest, which

otter is moving faster when she reaches the bottom of her hill?

A) Otter 1 is moving faster.

B) Otter 2 is moving faster.

C) The otter that took the shorter time is moving faster.

D) Both otters have the same speed at the bottom.

E) The heavier otter is moving faster, no matter which hill she used.

22)

4

23) A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless

surface. They both slide up the same frictionless hill with no air resistance. Which object rises to a

greater height?

A) The heavy object, because it has more mass to carry it up the hill.

B) The lightweight object, because the force of gravity on it is less.

C) The light object, because gravity slows it down less.

D) The heavy object, because it has greater initial kinetic energy.

E) They both slide to exactly the same height.

23)

24) A person stands on the edge of a cliff. She throws three identical rocks with the same speed. Rock

X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically

downward. If the ground at the base of the cliff is level, which rock hits the ground with the

greatest speed if there is no air resistance?

A) Rock X

B) Rock Y

C) Rock Z

D) They all hit the ground with the same speed.

24)

25) Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed twice

as high as Bill. If there is no air resistance, the maximum height of Joe’s ball will be

A) two times that of Bill’s ball.

B) four times that of Bill’s ball.

C) roughly 1.4 times that of Bill’s ball.

D) equal to that of Bill’s ball.

E) eight times that of Bill’s ball.

25)

26) A stone can slide down one of four different frictionless ramps, as shown in the figure. For which

ramp will the speed of the ball be the greatest at the bottom?

A) Ramp X

B) Ramp Y

C) Ramp Z

D) The speed of the ball will be the same for all ramps.

26)

5

27) A girl throws a stone from a bridge. Consider the following ways she might throw the stone. The

speed of the stone as it leaves her hand is the same in each case.

Case A: Thrown straight up.

Case B: Thrown straight down.

Case C: Thrown out at an angle of 45Â° above horizontal.

Case D: Thrown straight out horizontally.

In which case will the speed of the stone be greatest when it hits the water below if there is no

significant air resistance?

A) Case A

B) Case B

C) Case C

D) Case D

E) The speed will be the same in all cases.

27)

28) A heavy frog and a light frog jump straight up into the air. They push off in such away that they

both have the same kinetic energy just as they leave the ground. Air resistance is negligible. Which

of the following statements about these frogs are correct? (There could be more than one correct

choice.)

A) Just as they leave the ground, the heavier frog is moving faster than the lighter frog.

B) Both frogs reach the same maximum height.

C) The lighter frog goes higher than the heavier frog.

D) They both leave the ground with the same speed.

E) Just as they leave the ground, the lighter frog is moving faster than the heavier frog.

F) The heavier frog goes higher than the lighter frog.

28)

29) Two identical grasshoppers jump into the air with the same initial speed and experience no air

resistance. Grasshopper A goes straight up, but grasshopper B goes up at a 66Â° angle above the

horizontal. Which of the following statements about these grasshoppers are correct? (There could

be more than one correct choice.)

A) At their highest point, both of them have the same amount of kinetic energy.

B) At their highest point, both of them have the same amount of gravitational potential energy.

C) At their highest point, grasshopper B is moving faster than grasshopper A.

D) At their highest point, both of them have the same amount of mechanical energy.

E) At their highest point, grasshopper A has more gravitational potential energy than

grasshopper B.

29)

30) A heavy rock and a light rock are dropped from the same height and experience no significant air

resistance as they fall. Which of the following statements about these rocks are correct? (There

could be more than one correct choice.)

A) Both rocks have the same speed when they reach the ground.

B) The heavier rock reaches the ground before the lighter rock.

C) Both rocks have the same kinetic energy when they reach the ground.

D) Just as they were released, both rocks had the same amount of gravitational potential energy.

E) When they reach the ground, the heavier rock has more kinetic energy than the lighter rock.

30)

6

31) A heavy stone and a light stone are released from rest in such away that they both have the same

amount of gravitational potential energy just as they are released. Air resistance is negligibly small.

Which of the following statements about these stones are correct? (There could be more than one

correct choice.)

A) The stones must have been released from the same height.

B) The stones both have the same kinetic energy just as they reach the ground.

C) The stones both have the same speed just as they reach the ground.

D) The initial height of the light stone is greater than the initial height of the heavy stone.

E) Just as it reaches the ground, the light stone is traveling faster than the heavy stone.

31)

32) A 1-kg ball is released from a height of 6 m, and a 2-kg ball is released from a height of 3 m. Air

resistance is negligible as they fall. Which of the following statements about these balls are correct?

(There could be more than one correct choice.)

A) As they reach the ground, the 1-kg ball will be moving faster than the 2-kg ball.

B) Both balls will take the same time to reach the ground.

C) Both balls will reach the ground with the same speed.

D) Both balls will reach the ground with the same kinetic energy.

E) As they reach the ground, the 1-kg ball will have more kinetic energy than the 2-kg ball

because it was dropped from a greater height.

32)

33) A heavy dart and a light dart are launched vertically by identical ideal springs. Both springs were

initially compressed by the same amount. There is no significant air resistance. Which of the

following statements about these darts are correct? (There could be more than one correct choice.)

A) The heavy dart goes higher than the light dart.

B) The light dart goes higher than the heavy dart.

C) At the maximum height, both darts have the same gravitational potential energy.

D) Both darts began moving upward with the same initial speed.

E) Both darts reach the same maximum height.

33)

34) A heavy sled and a light sled, both moving horizontally with the same speed, suddenly slide onto

a rough patch of snow and eventually come to a stop. The coefficient of kinetic friction between the

sleds and the rough snow is the same for both of them. Which of the following statements about

these sleds are correct? (There could be more than one correct choice.)

A) Both sleds will slide the same distance on the rough snow before stopping.

B) The friction from the snow will do more negative work on the heavy sled than on the light

sled.

C) The friction from the snow will do the same amount of work on both sleds.

D) The light sled will slide farther on the rough snow than the heavy sled.

E) The heavy sled will slide farther on the rough snow than the light sled.

34)

35) A heavy sled and a light sled, both moving horizontally with the same kinetic energy, suddenly

slide onto a rough patch of snow and eventually come to a stop. The coefficient of kinetic friction

between the sleds and the rough snow is the same for both of them. Which of the following

statements about these sleds are correct? (There could be more than one correct choice.)

A) The light sled will slide farther on the rough snow than the heavy sled.

B) Both sleds will slide the same distance on the rough snow before stopping.

C) On the rough snow, the change in kinetic energy will be the same for both sleds.

D) The friction from the snow will do the same amount of work on both sleds.

E) The heavy sled will slide farther on the rough snow than the light sled.

35)

7

36) If a stone is dropped with an initial gravitational potential energy of 100 J but reaches the ground

with a kinetic energy of only 75 J, this is a violation of the principle of conservation of energy.

A) True B) False

36)

37) If the units of your answer are kg Â· m2/s3, which of the following types of quantities could your

answer be? (There could be more than one correct choice.)

A) work

B) potential energy

C) power

D) force

E) kinetic energy

37)

38) Two cyclists who weigh the same and have identical bicycles ride up the same mountain, both

starting at the same time. Joe rides straight up the mountain, and Bob rides up the longer road that

has a lower grade. Joe gets to the top before Bob. Ignoring friction and wind resistance, which one

of the following statements is true?

A) The amount of work done by Joe is equal to the amount of work done by Bob, but the

average power exerted by Joe is greater than that of Bob.

B) The amount of work done by Joe is greater than the amount of work done by Bob, and the

average power exerted by Joe is greater than that of Bob.

C) The average power exerted by Bob and Joe was the same, but Joe exerted more work in

getting there.

D) Bob and Joe exerted the same amount of work, and the average power of each cyclist was

also the same.

38)

39) Jill does twice as much work as Jack does and in half the time. Jill’s power output is

A) the same as Jack’s power output.

B) twice Jack’s power output.

C) four times Jack’s power output.

D) one-half as much as Jack’s power output.

E) one-fourth as much as Jack’s power output.

39)

40) A force produces power P by doing work W in a time T. What power will be produced by a force

that does six times as much work in half as much time?

A) 12P B) 6P C) 16P D) P E) 1

12

P

40)

41) An ornament of mass 40.0 g is attached to a vertical ideal spring with a force constant (spring

constant) of 20.0 N/m. The ornament is then lowered very slowly until the spring stops stretching.

How much does the spring stretch?

A) 0.0816 m B) 0.00200 m C) 0.0196 m D) 0.800 m E) 0.200 m

41)

42) A force of 30 N stretches a very light ideal spring 0.73 m from equilibrium. What is the force

constant (spring constant) of the spring?

A) 34 N/m B) 46 N/m C) 22 N/m D) 41 N/m

42)

43) A very light ideal spring stretches by 21.0 cm when it is used to hang a 135-N object. What is the

weight of a piece of electronic equipment that would stretch the spring by 44.9 cm if you hung the

equipment using the spring?

A) 289 N B) 405 N C) 176 N D) 63 N

43)

8

44) An object attached to a spring is pulled across a horizontal frictionless surface. If the force constant

(spring constant) of the spring is 45 N/m and the spring is stretched by 0.88 m when the object is

accelerating at 1.4 m/s2, what is the mass of the object?

A) 36 kg B) 28 kg C) 24 kg D) 31 kg

44)

45) A 3.0-kg brick rests on a perfectly smooth ramp inclined at 34Â° above the horizontal. The brick is

kept from sliding down the plane by an ideal spring that is aligned with the surface and attached

to a wall above the brick. The spring has a spring constant (force constant) of 120 N/m. By how

much does the spring stretch with the brick attached?

A) 24 cm B) 240 cm C) 14 cm D) 360 cm E) 36 cm

45)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

46) A very light ideal spring having a spring constant (force constant) of 8.2 N/cm is used to

lift a 2.2-kg tool with an upward acceleration of 3.25 m/s2. If the spring has negligible

length when it us not stretched, how long is it while it is pulling the tool upward?

46)

47) A very light ideal spring with a spring constant (force constant) of 2.5 N/cm pulls

horizontally on an 18-kg box that is resting on a horizontal floor. The coefficient of static

friction between the box and the floor is 0.65, and the coefficient of kinetic friction is 0.45.

(a) How long is the spring just as the box is ready to move?

(b) If the spring pulls the box along with a constant forward velocity of 1.75 m/s, how long

is the spring?

(c) How long is the spring if it pulls the box forward at a constant 2.75 m/s?

47)

48) A very light ideal spring of spring constant (force constant) 2.5 N/cm is 15 cm long when

nothing is attached to it. It is now used to pull horizontally on a 12.5-kg box on a perfectly

smooth horizontal floor. You observe that the box starts from rest and moves 96 cm during

the first 1.6 s of its motion with constant acceleration. How long is the spring during this

motion?

48)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

49) How much work would a child do while pulling a 12-kg wagon a distance of 4.3 m with a 22 N

force?

A) 67 J B) 95 J C) 109 J D) 52 J

49)

50) A child does 350 J of work while pulling a box from the ground up to his tree house at a steady

speed with a light rope. The tree house is 4.0 m above the ground. What is the mass of the box?

A) 6.7 kg B) 8.0 kg C) 5.3 kg D) 8.9 kg

50)

51) You carry a 7.0-kg bag of groceries 1.2 m above the ground at constant speed across a 2.7 m room.

How much work do you do on the bag in the process?

A) 157 J B) 185 J C) 82 J D) 0.00 J

51)

52) It requires 0.30 kJ of work to fully drive a stake into the ground. If the average resistive force on the

stake by the ground is 828 N, how long is the stake?

A) 0.31 m B) 0.23 m C) 0.36 m D) 0.41 m

52)

9

53) A crane lifts a 425 kg steel beam vertically upward a distance of 95 m. How much work does the

crane do on the beam if the beam accelerates upward at 1.8 m/s2? Neglect frictional forces.

A) 4.0 Ã— 105 J B) 2.7 Ã— 105J C) 4.7 Ã— 105 J D) 3.2 Ã— 105 J

53)

54) A traveler pulls on a suitcase strap at an angle 36Â° above the horizontal. If 555 J of work are done

by the strap while moving the suitcase a horizontal distance of 15 m, what is the tension in the

strap?

A) 52 N B) 56 N C) 46 N D) 37 N

54)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

55) A 500-kg elevator is pulled upward with a constant force of 5500 N for a distance of 50.0

m.

(a) What is the work done by the 5500-N force?

(b) What is the work done by gravity?

(c) What is the net work done on the elevator?

55)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

56) A 30-N box is pulled upward 6.0 m along the surface of a ramp that rises at 37Â° above the

horizontal. How much work does gravity do on the box during this process?

A) -110 J B) 120 J C) -180 J D) -140 J E) -1100 J

56)

57) Matthew pulls his little sister Sarah along the horizontal ground in a wagon. He exerts a force on

the wagon of 60.0 N at an angle of 37.0Â° above the horizontal. If he pulls her a distance of 12.0 m,

how much work does Matthew do?

A) 720 J B) 433 J C) 185 J D) 575 J

57)

58) Find the net work done by friction on a box that moves in a complete circle of radius 1.82 m on a

uniform horizontal floor. The coefficient of kinetic friction between the floor and the box is 0.25,

and the box weighs 65.0 N.

A) 1800 J B) 370 J C) 0 J D) 190 J

58)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

59) A 2.0-kg object is lifted vertically through 3.00 m by a 150-N force. How much work is

done on the object by gravity during this process?

59)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

60) A person carries a 25.0-N rock through the path shown in the figure, starting at point A and

ending at point B. The total time from A to B is 1.50 min. How much work did gravity do on the

rock between A and B?

A) 275 J B) 20.0 J C) 0 J D) 75 J E) 625 J

60)

10

61) A person carries a 2.00-N pebble through the path shown in the figure, starting at point A and

ending at point B. The total time from A to B is 6.75 min. How much work did gravity do on the

rock between A and B?

A) -36.0 J B) -56.0 J C) 56.0 J D) 30.0 J E) -30.0 J

61)

62) A stone with a mass of 1.0 kg is tied to the end of a light string which keeps it moving in a circle

with a constant speed of 4.0 m/s on a perfectly smooth horizontal tabletop. The radius of the path

is 0.60 m. How much work does the tension in the string do on the stone as it makes one-half of a

complete circle?

A) 0 J B) 40 J C) 100 J D) 3.8 J E) 80 J

62)

63) A force acts on an object, causing it to move parallel to the force. The graph in the figure shows this

force as a function of the position of the object. How much work does the force do as the object

moves from 4 m to 6 m?

A) 70 J B) 40 J C) 20 J D) 30 J E) 0 J

63)

64) A force acts on an object, causing it to move parallel to the force. The graph in the figure shows this

force as a function of the position of the object. How much work does the force do as the object

moves from 0 m to 4 m?

A) 20 J B) 0 J C) 30 J D) 40 J E) 70 J

64)

11

65) A force acts on an object, causing it to move parallel to the force. The graph in the figure shows this

force as a function of the position of the object. How much work does the force do as the object

moves from 6 m to 12 m?

A) 40 J B) 20 J C) 70 J D) 0 J E) 30 J

65)

66) A force acts on an object, causing it to move parallel to the force. The graph in the figure shows this

force as a function of the position of the object. How much work does the force do as the object

moves from 0 to 15 m?

A) 100 J B) 50 J C) 125 J D) 25 J E) 150 J

66)

67) The net force that an animal exerts on a large piece of fruit it has found is observed and is shown in

the graph in the figure. If the force is parallel to the motion of the fruit, how much work did the

animal do during the encounter?

A) 25 J B) 50 J C) 0 J D) 12.5 J E) 22 J

67)

68) The resultant force on an object over a 0.50-s time interval is plotted in the graph in the figure.

How much work did this force do on the object during the 0.50-s interval?

A) 22 J B) 50 J C) -25 J D) 12.5 J E) 0 J

68)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

69) How fast must a 6.0-kg cat run to have a kinetic energy of 150 J? 69)

12

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

70) How much kinetic energy does a 0.30-kg stone have if it is thrown at 44 m/s?

A) 580 J B) 440 J C) 510 J D) 290 J

70)

71) An object hits a wall and bounces back with half of its original speed. What is the ratio of the final

kinetic energy to the initial kinetic energy of the object?

A) 1/2 B) 1/8 C) 1/16 D) 1/4

71)

72) A 1000-kg car is moving at 15 km/h. If a 2000-kg truck has 23 times the kinetic energy of the car,

how fast is the truck moving?

A) 61 km/h B) 41 km/h C) 72 km/h D) 51 km/h

72)

73) What is the minimum energy needed to change the speed of a 1600-kg sport utility vehicle from

15.0 m/s to 40.0 m/s?

A) 40.0 kJ B) 10.0 kJ C) 0.960 MJ D) 1.10 MJ E) 20.0 kJ

73)

74) A 1.0-kg object moving in a certain direction has a kinetic energy of 2.0 J. It hits a wall and comes

back with half its original speed. What is the kinetic energy of this object at this point?

A) 0.25 J B) 0.50 J C) 1.0 J D) 2.0 J E) 4.0 J

74)

75) How much work must be done by frictional forces in slowing a 1000-kg car from 26.1 m/s to rest?

A) 4.77 Ã— 105 J B) 4.09 Ã— 105 J C) 2.73 Ã— 105 J D) 3.41 Ã— 105 J

75)

76) When a car of mass 1167 kg accelerates from 10.0 m/s to some final speed, 4.00 Ã— 105 J of work are

done. Find this final speed.

A) 22.4 m/s B) 30.8 m/s C) 25.2 m/s D) 28.0 m/s

76)

77) A 10-kg dog is runnng with a speed of 5.0 m/s. What is the minimum work required to stop the

dog in 2.40 s?

A) 100 J B) 75 J C) 50 J D) 125 J

77)

78) How large a net force is required to accelerate a 1600-kg SUV from rest to a speed of 25 m/s in a

distance of 200 m?

A) 0 N B) 2500 N C) 200 N D) 400 N E) 1600 N

78)

79) A 100-N force has a horizontal component of 80 N and a vertical component of 60 N. The force is

applied to a cart on a level frictionless floor. The cart starts from rest and moves 2.0 m horizontally

along the floor due to this force. What is the cart’s final kinetic energy?

A) zero B) 160 J C) 200 J D) 120 J

79)

80) A 1000-kg car experiences a net force of 9500 N while slowing down from 30 m/s to 15.9 m/s. How

far does it travel while slowing down?

A) 31 m B) 41 m C) 37 m D) 34 m

80)

81) A stone initially moving at 8.0 m/s on a level surface comes to rest due to friction after it travels 11

m. What is the coefficient of kinetic friction between the stone and the surface?

A) 0.25 B) 0.43 C) 0.30 D) 0.13 E) 0.80

81)

13

82) A sled having a certain initial speed on a horizontal surface comes to rest after traveling 10 m. If

the coefficient of kinetic friction between the object and the surface is 0.20, what was the initial

speed of the object?

A) 8.9 m/s B) 9.8 m/s C) 3.6 m/s D) 7.2 m/s E) 6.3 m/s

82)

83) On an alien planet, an object moving at 4.0 m/s on the horizontal ground comes to rest after

traveling a distance of 10 m. If the coefficient of kinetic friction between the object and the surface

is 0.20, what is the value of g on that planet?

A) 12 m/s2 B) 10 m/s2 C) 6.0 m/s2 D) 8.0 m/s2 E) 4.0 m/s2

83)

84) A driver, traveling at 22 m/s, slows down her 2000 kg truck to stop for a red light. What work is

done on the truck by the friction force of the road?

A) -2.2 Ã— 104 J B) -4.4 Ã— 104 J C) -9.7 Ã— 105 J D) -4.8 Ã— 105 J

84)

85) The kinetic friction force that a horizontal surface exerts on a 60.0-kg object is 50.0 N. If the initial

speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?

A) 375 m B) 15.0 m C) 30.0 m D) 750 m

85)

86) A stone is moving on a rough level surface. It has 24 J of kinetic energy, and the friction force on it

is a constant 0.50 N. What is the maximum distance it can slide?

A) 48 m B) 24 m C) 2.0 m D) 12 m

86)

87) In a ballistics test, a 28-g bullet pierces a sand bag that is 30 cm thick. If the initial bullet velocity

was 55 m/s and it emerged from the sandbag moving at 18 m/s, what was the magnitude of the

friction force (assuming it to be constant) that the bullet experienced while it traveled through the

bag?

A) 130 N B) 1.3 N C) 38 N D) 13 N

87)

88) A certain car traveling at 34.0 mph skids to a stop in 29 meters from the point where the brakes

were applied. In approximately what distance would the car have stopped had it been going 105.4

mph?

A) 29 m B) 158 m C) 279 m D) 90 m E) 51 m

88)

89) The horizontal force that an animal exerts on a large fruit it has found is observed and is shown in

the graph in the figure. If the fruit was initially sliding on the frictionless ground at 5.5 cm/s when

the animal first grabbed it, by how much did the animal change its kinetic energy during this

encounter?

A) 25 J B) 50 J C) 22 J D) 0 J E) 12.5 J

89)

14

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

90) The graph in the figure shows the magnitude of the net horizontal force Fx on a 25-kg

package as a function of the position x of the package. Just before the force was applied,

the package was originally sliding at 6.0 m/s in the +x direction on a smooth horizontal

floor. Find the x component of the velocity of the package just after the force has stopped

in each of the following cases.

(a) The force is applied in the same direction as the original velocity of the box.

(b) The force is applied in the opposite direction to the original velocity of the box.

90)

91) How high a hill would a 75-kg hiker have to climb to increase her gravitational potential

energy by 10,000 J?

91)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

92) You do 116 J of work while pulling your sister back on a fritctionless swing, whose chain is 5.10 m

long, until the swing makes an angle of 32.0Â° with the vertical. What is your sister’s mass?

A) 15.3 kg B) 19.0 kg C) 13.0 kg D) 17.6 kg

92)

93) A tennis ball bounces on the floor three times, and each time it loses 23.0% of its energy due to

heating. How high does it bounce after the third time, if we released it 4.0 m from the floor?

A) 180 mm B) 180 cm C) 240 cm D) 18 cm

93)

94) A 10-kg mass, hung by an ideal spring, causes the spring to stretch 2.0 cm. What is the spring

constant (force constant) for this spring?

A) 0.20 N/cm

B) 49 N/cm

C) 0.0020 N/cm

D) 5.0 N/cm

E) 20 N/m

94)

95) An ideal spring stretches by 21.0 cm when a 135-N object is hung from it. If instead you hang a

fish from this spring, what is the weight of a fish that would stretch the spring by 31.0 cm?

A) 91 N B) 199 N C) 145 N D) 279 N

95)

96) An ideal spring has a spring constant (force constant) of 2500 N/m. is stretched 4.0 cm. How much

work is required to stretch the spring by 4.0 cm?

A) 0.00 J B) 3.0 J C) 4.0 J D) 2.0 J E) 1.0 J

96)

15

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

97) You want to store 1,000 J of energy in an ideal spring when it is compressed by only 2.5

cm. What should be the force constant (spring constant) of this spring?

97)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

98) If 4.0 J of work are performed in stretching an ideal spring with a spring constant (force constant)

of 2500 N/m, by what distance is the spring stretched?

A) 3.2 m B) 0.3 cm C) 5.7 cm D) 3.2 cm E) 5.7 m

98)

99) If the work done to stretch an ideal spring by 4.0 cm is 6.0 J, what is the spring constant (force

constant) of this spring?

A) 7500 N/m B) 300 N/m C) 6000 N/m D) 3500 N/m E) 3000 N/m

99)

100) An ideal spring has a spring constant (force constant) of 60 N/m. How much energy does it store

when it is stretched by 1.0 cm?

A) 60 J B) 0.30 J C) 0.0030 J D) 600 J

100)

101) How much work is required to stretch an ideal spring of spring constant (force constant) 40 N/m

from x = 0.20 m to x = 0.25 m if the unstretched position is at x = 0.00 m?

A) 0.80 J B) 0.050 J C) 0.45 J D) 1.3 J

101)

102) An ideal spring with a force constant (spring constant) of 15 N/m is initially compressed by 3.0 cm

from its uncompressed position. How much work is required to compress the spring an additional

4.0 cm?

A) 0.0068 J B) 0.024 J C) 0.012 J D) 0.030 J

102)

103) It takes 87 J of work to stretch an ideal spring from 1.4 m to 2.9 m from equilibrium. What is the

value of the spring constant (force constant) of this spring?

A) 27 N/m B) 77 N/m C) 39 N/m D) 52 N/m

103)

104) An ideal spring with a spring constant (force constant) of 22 N/mis stretched from equilibrium to

2.9 m. How much work is done in the process?

A) 93 J B) 47 J C) 186 J D) 121 J

104)

105) A rock falls from a vertical cliff that is 4.0 m tall and experiences no significant air resistance as it

falls. At what speed will its gravitational potential energy (relative to the base of the cliff) be equal

to its kinetic energy?

A) 4.4 m/s B) 13 m/s C) 8.9 m/s D) 3.1 m/s E) 6.3 m/s

105)

106) A block slides down a frictionless inclined ramp and experiences no significant air resistance. If the

ramp angle is 17.0Â° above the horizontal and the length of the surface of the ramp is 20.0 m, find

the speed of the block as it reaches the bottom of the ramp, assuming it started sliding from rest at

the top.

A) 19.6 m/s B) 7.57 m/s C) 114 m/s D) 10.7 m/s

106)

16

107) A prankster drops a water balloon from the top of a building. If the balloon is traveling at 29.1 m/s

when it strikes a window ledge that is 1.5 m above the ground, how tall is the building? Neglect air

resistance.

A) 47 m B) 43 m C) 45 m D) 46 m

107)

108) A spring-loaded dart gun is used to shoot a dart straight up into the air, and the dart reaches a

maximum height of 24 meters. The same dart is shot up a second time from the same gun, but this

time the spring is compressed only half as far (compared to the first shot). How far up does the

dart go this time (neglect all friction and assume the spring is ideal)?

A) 12 m B) 6.0 m C) 48 m D) 3.0 m

108)

109) A bead is moving with a speed of 20 m/s at position A on the track shown in the figure. This track

is friction-free, and there is no appreciable air resistance. What is the speed of the bead at point C?

A) 0 m/s

B) 20 m/s

C) 69 m/s

D) 34 m/s

E) We cannot solve this problem without knowing the mass of the bead.

109)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

110) A frictionless simple pendulum, with a small but dense 4.4-kg mass at the end and a

length of 75 cm, is released from rest at an angle of 50Â° with the vertical.

(a) To what height above its lowest point does the mass swing on the other side?

(b) What is the speed of the mass at the bottom of the swing?

110)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

111) The figure shows a famous roller coaster ride. You can ignore friction. If the roller coaster leaves

point Q from rest, what is its speed at the top of the 25-m peak (point S)?

A) 22 m/s B) 62 m/s C) 44 m/s D) 10 m/s E) 120 m/s

111)

112) What is the minimum energy needed to lift a 1.0-kg rocket to a height of 200 km and to give it a

speed of 8.0 km/s at that height? (Neglect air resistance and the small decrease in g over that

distance.)

A) 34 kJ B) 34 MJ C) 34 TJ D) 34 J E) 34 GJ

112)

17

113) Assuming negligible friction, what spring constant (force constant) would be needed by the spring

in a “B-B gun” to fire a 10-g pellet to a height of 100 m if the spring is initially compressed by 0.10

m?

A) 200 N/m

B) 0.0020 N/m

C) 20 N/m

D) 2000 N/cm

E) 20 N/cm

113)

114) If a spring-operated gun can shoot a pellet to a maximum height of 100 m on Earth, how high

could the pellet rise if fired on the Moon, where g = 1.6 m/s2?

A) 610 m B) 17 m C) 3.6 km D) 160 m E) 100 m

114)

115) A 60-kg skier pushes off the top of a frictionless hill with an initial speed of 4.0 m/s. How fast will

she be moving after dropping 10 m in elevation? Air resistance is negligible.

A) 49 m/s B) 0.15 km/s C) 10 m/s D) 0.20 km/s E) 15 m/s

115)

116) A toy rocket that weighs 10 N blasts straight up from ground level with an initial kinetic energy of

40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height

above the ground does it rise, assuming no air resistance?

A) 14 m B) 10 m C) 1.0 m D) 24 m

116)

117) A 5.0-N projectile leaves the ground with a kinetic energy of 220 J. At the highest point in its

trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise

if there was no air resistance?

A) 24 m

B) 44 m

C) 10 m

D) 20 m

E) It is impossible to determine the height without knowing the angle of launch.

117)

118) In the figure, a ball hangs by a very light string. What is the minimum speed of the ball at the

bottom of its swing (point B) in order for it to reach point A, which is 1.0 m above the bottom of the

swing?

A) 2.2 m/s B) 4.9 m/s C) 4.4 m/s D) 3.1 m/s

118)

119) A 1500-kg car moving at 25 m/s hits an initially uncompressed horizontal ideal spring with spring

constant (force constant) of 2.0 Ã— 106 N/m. What is the maximum distance the spring compresses?

A) 0.34 m B) 0.68 m C) 0.51 m D) 0.17 m

119)

18

120) A small but dense 2.0-kg stone is attached to one end of a very light rod that is 1.2 m long. The

other end of the rod is attached to a frictionless pivot. The rod is raised until it is vertical, with the

stone above the pivot. The rod is released and the stone moves in a vertical circle with no air

resistance. What is the tension in the rod as the stone moves through the bottom of the circle?

A) 80 N B) 60 N C) 40 N D) 20 N E) 100 N

120)

121) In a museum exhibit of a simple pendulum, a very small but dense 6.0-kg ball swings from a very

light 2.5-m wire. The ball is released from rest when the pendulum wire makes a 65Â° angle with

the vertical, and it swings in a circular arc with no appreciable friction or air resistance. What is the

tension in the wire just as the ball swings through its lowest position?

A) 0 N B) 11 N C) 68 N D) 130 N E) 59 N

121)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

122) A roller coaster starting from rest descends 35 meters in its initial drop and then rises 23

meters when it goes over the first hill, which has a circular shape over the top. If a

passenger at the top of the hill feels an apparent weight equal to one-half of her normal

weight, what is the radius of curvature of the first hill? Neglect any frictional losses.

122)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

123) A roller coaster starts from rest at a height h at the left side of a loop-the-loop, as shown in the

figure. It is not attached to the track in anyway, and there is no friction from the track or from air

resistance. If the radius of the loop is R = 6.0 m, what is the minimum height h for which the roller

coaster will not fall off the track at the top of the loop?

A) 8.5 m B) 12 m C) 15 m D) 21 m E) 18 m

123)

124) A stone is released from rest at a height h at the left side of a loop-the-loop, as shown in the figure.

There is no appreciable friction from the track or from air resistance. If the radius of the loop is R,

what is the minimum height h for which the stone will not fall off the track at the top of the loop?

A) 3.5 R B) 3.0 R C) 2.5 R D) 2.0 R E) 2R

124)

19

125) A small 1.4-N stone slides down a frictionless bowl, starting from rest at the rim. The bowl itself is

a hemisphere of radius 75 cm. Just as the stone reaches the bottom of the bowl, how hard is the

bowl pushing on it?

A) 0.70 N B) 5.6 N C) 4.2 N D) 2.8 N E) 1.4 N

125)

126) A 30-N stone is dropped from a height of 10 m and strikes the ground with a speed of 13 m/s.

What average force of air friction acted on the stone as it fell?

A) 7.2 N B) 4.1 N C) 1.2 N D) 2.9 N E) 0.13 kN

126)

127) A 60-kg skier starts from rest from the top of a 50-m high slope. If the work done by friction is

-6.0 kJ, what is the speed of the skier on reaching the bottom of the slope?

A) 24 m/s B) 31 m/s C) 17 m/s D) 28 m/s

127)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

128) A 7.5-kg otter slides down a hill, starting from rest at the top. The sloping surface of the

hill is 8.8 m long, and the top is 6.5 m above the base. If the speed of the otter at the

bottom of the hill is 9.2 m/s, how much energy was lost to nonconservative forces on the

hill?

128)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

129) An object with a mass of 10 kg is initially at rest at the top of a frictionless inclined plane that rises

at 30Â° above the horizontal. At the top, the object is initially 8.0 m from the bottom of the incline, as

shown in the figure. When the object is released from this position, it eventually stops at a distance

d from the bottom of the inclined plane along a horizontal surface, as shown. The coefficient of

kinetic friction between the horizontal surface and the object is 0.20, and air resistance is negligible.

Find the distance d.

A) 15 m B) 5.0 m C) 25 m D) 10 m E) 20 m

129)

130) On a planet where g = 10.0 m/s2 and air resistance is negligible, a sled is at rest on a rough inclined

hill rising at 30Â° as shown in the figure. The object is allowed to move and it stops on a rough

horizontal surface, at a distance of 4.0 m from the bottom of the hill. The coefficient of kinetic

friction on the hill is 0.40. What is the coefficient of kinetic friction between the horizontal surface

and the sled?

A) 0.40 B) 0.60 C) 0.10 D) 0.31 E) 0.20

130)

20

131) A 0.12-kg block is held in place against the spring by a 35-N horizontal external force. The external

force is removed, and the block is projected with a velocity Î½1 = 1.2 m/s when it separates from the

spring, as shown in the figure. The block descends a ramp and has a velocity Î½2 = 1.4 m/s at the

bottom of the ramp. The track is frictionless between points A and B. The block enters a rough

section at B, extending to E. The coefficient of kinetic friction between the block and the rough

surface is 0.26. The block moves on to D, where it stops. By how many centimeters was the spring

initially compressed?

A) 0.49 cm B) 0.99 cm C) 0.67 cm D) 0.26 cm E) 0.18 cm

131)

132) As shown in the figure, a 1.45-kg block is held in place against the spring by a 21-N horizontal

external force. The external force is removed, and the block is projected with a velocity Î½1 = 1.2 m/s

as it separates from the spring. The block descends a ramp and has a velocity Î½2 = 2.1 m/s at the

bottom. The track is frictionless between points A and B. The block enters a rough section at B,

extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.29.

The velocity of the block is Î½3 = 1.4 m/s at C. The block moves on to D, where it stops. How much

work is done by friction between points B and C?

A) -1.8 J B) -3.6 J C) -6.4 J D) -7.0 J E) -14 J

132)

21

133) A 0.46-kg block is held in place against the spring by a 30-N horizontal external force. The external

force is removed, and the block is projected with a velocity Î½1 = 1.2 m/s upon separation from the

spring, as shown in the figure. The block descends a ramp and has a velocity Î½2 = 1.5 m/s at the

bottom. The track is frictionless between points A and B. The block enters a rough section at point

B, extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.38.

The velocity of the block is Î½3 = 1.4 m/s at point C. The block moves on to D, where it stops. What

distance does the block travel between points B and D?

A) 0.60 m B) 0.30 m C) 0.039 m D) 0.40 m E) 0.26 m

133)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

134) A sled is moving along a horizontal surface with a speed of 5.7 m/s. It then slides up a

rough hill having a slope of 11Â° above the horizontal. The coefficient of kinetic friction

between the sled and the surface of the hill is 0.26. How far along the surface does the

block travel up the incline?

134)

135) The figure shows two crates, each of mass m = 24 kg, that are connected by a very light

wire. The coefficient of kinetic friction between the crate on the inclined surface and the

surface itself is 0.31. Find the speed of the crates after they have moved 1.6 m starting from

rest.

135)

136) As shown in the figure, a 4.0-kg block is moving at 5.0 m/s along a horizontal frictionless

surface toward an ideal spring that is attached to a wall. After the block collides with the

spring, the spring is compressed a maximum distance of 0.68 m. What is the speed of the

block when the spring is compressed to only one-half of the maximum distance?

136)

22

137) How many joules of energy are used by a 2.0 hp motor that runs for 1.0 hour? (1 hp = 746

W)

137)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

138) A child pulls on a wagon with a force of 75 N. If the wagon moves a total of 42 m in 3.1 min, what

is the average power delivered by the child?

A) 26 W B) 22 W C) 17 W D) 21 W

138)

139) How many joules of energy are used by a 1.0-hp motor that runs for 1.0 hour? (1 hp = 746 W)

A) 4.8 J B) 3.6 kJ C) 2.7 MJ D) 45 kJ

139)

140) A 1500-kg car accelerates from rest to 25 m/s in 7.0 s. What is the average power delivered by the

engine? (1 hp = 746 W)

A) 70 hp B) 80 hp C) 60 hp D) 90 hp

140)

141) At what minimum rate is a 60.0-kg boy using energy when, in 8.00 s, he runs up a flight of stairs

that is 10.0-m high?

A) 75.0 W B) 735 W C) 48.0 W D) 4.80 kW

141)

142) If electricity costs 7.06Â¢/kWÂ·h, how much would it cost you to run a 120-W stereo system 4.0 hours

per day for 4.0 weeks?

A) $1.62 B) $0.14 C) $2.66 D) $0.95

142)

143) A 1321-kg car climbs a 5.0Â° slope at a constant speed of 80.0 km/h. Assuming that air resistance

may be neglected, at what rate (in kW) must the engine deliver energy to the drive wheels of the

car?

A) 25 kW B) 287 kW C) 48 kW D) 38 kW

143)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

144) A typical incandescent light bulb consumes 75 W of power and has a mass of 30 g. You

want to save electrical energy by dropping the bulb from a height great enough so that the

kinetic energy of the bulb when it reaches the floor will be the same as the energy it took to

keep the bulb on for 1.0 hour. From what height should you drop the bulb, assuming no

air resistance and constant g?

144)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

145) What is the net power needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s

to 40.0 m/s in 4.00 seconds?

A) 10.0 kW B) 14.0 kW C) 100 kW D) 140 kW E) 275 kW

145)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

146) Water flows over a waterfall that is 20 m high at the rate of 4.0 Ã— 104 kg/s. If this water

powers an electric generator with a 40% efficiency, how many watts of electric power can

be supplied?

146)

23

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

147) A certain battery charger uses 12 W of power. At 6.0 cents per kilowatt-hour, how much does it

cost to charge batteries for a full day?

A) 1.4Â¢ B) 2.3Â¢ C) 1.7Â¢ D) 75Â¢ E) 28Â¢

147)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

148) A family goes on vacation for one week but forgets to turn off an electric fan that

consumes electricity at the rate of 200 W. If the cost of electricity is 12.0Â¢/kWÂ·h how much

does it cost (to the nearest penny) to run the fan for the week?

148)

149) Suppose you left five 100-W light bulbs burning in the basement for two weeks. If

electricity costs 10.0Â¢/kWÂ·h, (a) how much did the electricity cost (to the nearest dollar) to

leave those bulbs on, and (b) how many joules of electrical energy did they consume?

149)

150) Rita raises a 10kg package to a height of 2.5 m in 2.0 s.

(a) How much work did she do on the package?

(b) How much power was expended on the package?

(c) If she were to raise the package in 1.0 s rather than 2.0 s, how do the work and power

change?

150)

151) In a physical fitness program, a woman who weighs 510 N runs up four flights of stairs in

22 s. Each flight rises 3.1 m. (1 hp = 746 W)

(a) What is her total change in potential energy?

(b) What was the minimum average power (in watts) that she expended during the 22 s?

(c) What horsepower motor would be required to generate the same power?

151)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

152) A sand mover at a quarry lifts 2,000 kg of sand per minute a vertical distance of 12 m. The sand is

initially at rest and is discharged at the top of the sand mover with speed 5.0 m/s into a loading

chute. What minimum power must be supplied to this machine?

A) 4.3 kW B) 520 W C) 3.9 kW D) 6.7 kW E) 1.1 kW

152)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

153) A 100%-efficient engine is being used to raise a 89-kg crate vertically upward at a steady

rate. If the power output of the engine is 1620 W, how long does it take the engine to lift

the crate a vertical distance of 18.7 m? Friction in the system is negligible.

153)

24

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

154) The net force that an animal exerts on a large fruit it has found is observed over a 10-s interval and

is shown in the graph in the figure. What was the average power delivered to the fruit by the

animal over this time interval?

A) 1.3 W B) 5.0 W C) 2.2 W D) 0.00 W E) 2.5 W

154)

25

Answer Key

Testname: UNTITLED6

1) B

2) E

3) C

4) C

5) A

6) B

7) C

8) A

9) D

10) C

11) C

12) A

13) B

14) B

15) B

16) A, B, E

17) E

18) E

19) B

20) D

21) C

22) D

23) E

24) D

25) B

26) D

27) E

28) B, E

29) C, D, E

30) A, E

31) B, D, E

32) A, D

33) B, C

34) A, B

35) A, C, D

36) B

37) C

38) A

39) C

40) A

41) C

42) D

43) A

44) B

45) C

46) 3.5 cm

47) (a) 46 cm (b) 32 cm (c) 32 cm

48) 19 cm

49) B

50) D

26

Answer Key

Testname: UNTITLED6

51) D

52) C

53) C

54) C

55) (a) 275 Kj (b) -245 kJ (c) 30.0 kJ

56) A

57) D

58) D

59) -59 J

60) C

61) E

62) A

63) C

64) A

65) E

66) C

67) A

68) E

69) 7.1 m/s

70) D

71) D

72) D

73) D

74) B

75) D

76) D

77) D

78) B

79) B

80) D

81) C

82) E

83) E

84) D

85) A

86) A

87) A

88) C

89) A

90) (a) +8.2 m/s (b) +2.0 m/s

91) 14 m

92) A

93) B

94) B

95) B

96) D

97) 3.2 Ã— 106 m/m

98) C

99) A

100) C

27

Answer Key

Testname: UNTITLED6

101) C

102) D

103) A

104) A

105) E

106) D

107) C

108) B

109) D

110) (a) 27 cm (b) 2.3 m/s

111) A

112) B

113) E

114) A

115) E

116) B

117) D

118) C

119) B

120) E

121) D

122) 48 m

123) C

124) C

125) C

126) B

127) D

128) 160 J

129) E

130) D

131) A

132) A

133) B

134) 3.7 m

135) 1.9 m/s

136) 4.3 m/s

137) 5.4 MJ

138) C

139) C

140) D

141) B

142) D

143) A

144) 920 km

145) E

146) 3.1 MW

147) C

148) $4.03

149) (a) $17 (b) 6.05 Ã— 108 J

150) (a) 0.25 Kj (b) 0.12 kW (c) the same work, but the power doubles

28

Answer Key

Testname: UNTITLED6

151) (a) 6.3 kJ (b) 290 W (c) 0.39 hp

152) A

153) 10 s

154) E

29

Exam

Name___________________________________

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

1) A rubber ball and a lump of clay have equal mass. They are thrown with equal speed against a

wall. The ball bounces back with nearly the same speed with which it hit. The clay sticks to the

wall. Which one of these objects experiences the greater momentum change?

A) the clay

B) the ball

C) Both of them experience the same non-zero momentum change.

D) Both of them experience zero momentum change.

1)

2) Which of the following quantities are units of momentum? (There could be more than one correct

choice.)

A) N Â· m B) N Â· s C) kg Â· s/m D) kg Â· m2/s2 E) kg Â· m/s

2)

3) A tiger is running in a straight line. If we double both the mass and speed of the tiger, the

magnitude of its momentum will increase by what factor?

A) 2 B) 2 C) 16 D) 4 E) 8

3)

4) A very elastic rubber ball is dropped from a certain height and hits the floor with a downward

speed v. Since it is so elastic, the ball bounces back with the same speed v going upward. Which of

the following statements about the bounce are correct? (There could be more than one correct

choice.)

A) The ball had the same momentum just before and just after the bounce.

B) The ball’s momentum was conserved during the bounce.

C) The magnitude of the ball’s momentum was the same just before and just after the bounce.

D) None of the above statements are correct.

4)

5) The momentum of an isolated system is conserved

A) in both elastic and inelastic collisions.

B) only in elastic collisions.

C) only in inelastic collisions.

5)

6) Two friends are standing on opposite ends of a canoe that is initially at rest with respect to a

frictionless lake. The person in the front throws a very massive ball toward the back, and the

person in the back catches it. After the ball is caught, the canoe is

A) moving forward. B) stationary. C) moving backward.

6)

7) You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you.

You have two choices about what to do with the ball: either catch the ball or deflect it back toward

your friend with the same speed as it was originally thrown. Which choice should you make in

order to maximize your speed on the skateboard?

A) Catch the ball.

B) Deflect the ball back.

C) Your final speed on the skateboard will be the same regardless whether you catch the ball or

deflect the ball.

7)

1

8) A small car meshes with a large truck in a head-on collision. Which of the following statements

concerning the magnitude of the momentum change during the collision is correct? (There could

be more than one correct choice.)

A) The small car and the truck experience the same magnitude momentum change.

B) The magnitude of the momentum change experienced by each one is directly proportional to

its mass.

C) The truck experiences the greater magnitude momentum change.

D) The small car experiences the greater magnitude momentum change.

E) The magnitude of the momentum change experienced by each one is inversely proportional

to its mass.

8)

9) A small car meshes with a large truck in a head-on collision. Which of the following statements

concerning the momentum during the collision are correct? (There could be more than one correct

choice.)

A) The momentum of the car is conserved.

B) The car and the truck must undergo the same change in speed.

C) The momentum of the car-truck system is conserved, but the momentum of each one

separately is not conserved.

D) The momentum of the car and the momentum of the truck are each conserved.

E) The momentum of the truck is conserved.

9)

10) Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on

into an identical car also going 30 mph. In the second option you are driving 30 mph and crash

head-on into a stationary brick wall. In neither case does your car bounce back from the thing it

hits, and the collision time is the same in both cases. Which of these two situations would result in

the greater impact force on your car?

A) The force would be the same in both cases.

B) hitting the other car

C) hitting the brick wall

D) None of the above choices are correct.

10)

11) A rocket explodes into two fragments, one 25 times heavier than the other. The magnitude of the

momentum change of the lighter fragment is

A) 1/25 as great as the momentum change of the heavier fragment.

B) The same as the momentum change of the heavier fragment.

C) 5 times as great as the momentum change of the heavier fragment.

D) 1/4 as great as the momentum change of the heavier fragment.

E) 25 times as great as the momentum change of the heavier fragment.

11)

12) Which of the following quantities are units of impulse? (There could be more than one correct

choice.)

A) N Â· m B) kg Â· m2/s2 C) N Â· s D) kg Â· m/s E) kg Â· s/m

12)

13) Three cars, car X, car Y, and car Z, begin accelerating from rest at the same time. Car X is more

massive than car Y, which is more massive than car Z. The net accelerating force exerted on each

car is identical. After 10 seconds, which car has the most amount of momentum?

A) They all have the same amount of momentum.

B) Car X

C) Car Y

D) Car Z

13)

2

14) During World War I, Germany used a “Big Bertha” cannon to hurl shells into Paris 30 miles away.

This gun also had a very long barrel. What was the reason for using a long barrel in these guns?

A) to exert a larger force on the shells

B) to allow the force of the expanding gases from the gunpowder to act for a longer time

C) to reduce frictional losses

D) to reduce the force exerted on the bullet due to the expanding gases from the gunpowder

E) to increase the force exerted on the bullet due to the expanding gases from the gunpowder

14)

15) In a collision between two unequal masses, which mass receives a greater magnitude impulse?

A) the smaller mass

B) the larger mass

C) They receive equal impulses.

15)

16) Identical forces act for the same length of time on two different objects. The magnitude of the

change in momentum of the lighter object is

A) exactly equal to the magnitude of the change in momentum of the larger mass.

B) zero.

C) larger than the magnitude of the change in momentum of the larger mass.

D) smaller than the magnitude of the change in momentum of the larger mass, but not zero.

E) There is not enough information to answer the question.

16)

17) A very light ping-pong ball moving east at a speed of 4 m/s collides with a very heavy stationary

bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very

slowly to the east. Which object experiences the greater magnitude impulse during the collision?

A) Neither; both experienced the same magnitude impulse.

B) the bowling ball

C) the Ping-Pong ball

D) It is impossible to tell since the actual mass values are not given.

E) It is impossible to tell since the velocities after the collision are unknown.

17)

18) A small car meshes with a large truck in a head-on collision. Which of the following statements

concerning the magnitude of the average force during the collision is correct?

A) The force experienced by each one is directly proportional to its mass.

B) The force experienced by each one is inversely proportional to its mass.

C) The truck experiences the greater average force.

D) The small car experiences the greater average force.

E) The small car and the truck experience the same average force.

18)

19) In an inelastic collision involving an isolated system, the final total momentum is

A) more than the initial momentum.

B) exactly the same as the initial momentum.

C) less than the initial momentum.

19)

3

20) A 5-kg ball collides inelastically head-on with a 10-kg ball, which is initially stationary. Which of

the following statements is true? (There could be more than one correct choice.)

A) The magnitude of the change of velocity the 5-kg ball experiences is less than that of the

10-kg ball.

B) The magnitude of the change of velocity the 5-kg ball experiences is greater than that of the

10-kg ball.

C) The magnitude of the change of the momentum of the 5-kg ball is equal to the magnitude of

the change of momentum of the 10-kg ball.

D) The magnitude of the change of velocity the 5-kg ball experiences is equal to that of the

10-kg ball.

E) Both balls lose all their momentum since the collision is inelastic.

20)

21) In a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away with

the same velocity as the cue ball had originally. Both balls have the same mass. This type of

collision is

A) elastic. B) somewhat inelastic. C) completely inelastic.

21)

22) In the figure, determine the character of the collision. The masses of the blocks, and the velocities

before and after, are shown. The collision is

A) completely inelastic.

B) partially inelastic.

C) perfectly elastic.

D) characterized by an increase in kinetic energy.

E) not possible because momentum is not conserved.

22)

23) In the figure showing an isolated system, determine the character of the collision. The masses of the

blocks, and the velocities before and after, are shown. The collision is

A) perfectly elastic.

B) completely inelastic.

C) partially inelastic.

D) characterized by an increase in kinetic energy.

E) not possible because momentum is not conserved.

23)

4

24) In the figure, determine the character of the collision. The masses of the blocks, and the velocities

before and after, are shown. The collision is

A) partially inelastic.

B) completely inelastic.

C) perfectly elastic.

D) characterized by an increase in kinetic energy.

E) not possible because momentum is not conserved.

24)

25) A 2.0-kg ball moving eastward at 3.0 m/s suddenly collides with and sticks to a 4.0-kg ball moving

northward at 2.0 m/s. What is the magnitude of the momentum of this system just after the

collision?

A) 2.0 kg Â· m/s

B) 8.0 kg Â· m/s

C) 6.0 kg Â· m/s

D) 10 kg Â· m/s

E) 14 kg Â· m/s

25)

26) An egg falls from a bird’s nest in a tree and feels no effects due to the air. As it falls,

A) only its momentum is conserved.

B) both its mechanical energy and its momentum are conserved.

C) only its kinetic energy is conserved.

D) both its kinetic energy and its momentum are conserved.

E) only its mechanical energy is conserved.

26)

27) If a quantity you calculated had units of kg Â· m/s, what type of quantity could it be? (There could

be more than one correct choice.)

A) kinetic energy

B) impulse

C) momentum

D) work

E) force

27)

28) A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the

collision, the kinetic energy of the system

A) is half as much as before.

B) is one quarter as much as before.

C) is one fourth as much as before.

D) is the same as before.

E) is one third as much as before.

28)

5

29) A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v

right after the bounce. As a result of this bounce, which of the following quantities of the ball are

conserved? (There could be more than one correct choice.)

A) both the momentum and the kinetic energy of the ball

B) the kinetic energy of the ball

C) the momentum of the ball

D) None of the above quantities are conserved.

29)

30) On a horizontal frictionless air table, a puck runs into an ideal horizontal spring that is fastened to

the table. The puck compresses the spring by 15 cm before coming to rest. During the compression

process, which quantities are conserved?

A) only the momentum of the puck

B) only the kinetic energy of the puck

C) the momentum and the mechanical energy of the puck

D) only the mechanical energy (kinetic plus potential) of the puck

E) the momentum and the kinetic energy of the puck

30)

31) Two objects of different mass have equal, non-zero kinetic energies. Which object has the greater

magnitude momentum?

A) the lighter object

B) the heavier object

C) They both have the same magnitude momentum.

31)

32) Two objects of different masses have momentum of equal, non-zero magnitude. Which object has

more kinetic energy?

A) the lighter object

B) the heavier object

C) They both have the same kinetic energy.

32)

33) If you want to double the kinetic energy of a gas molecule, by what factor must you increase its

momentum?

A) 16 B)2 2 C)4 D)2 E) 2

33)

34) If you want to double the momentum of a gas molecule, by what factor must you increase its

kinetic energy?

A) 2 2 B) 16 C) 2 D)2 E)4

34)

35) A firecracker explodes in midair and breaks up into many fragments. Which of the following

statements are true regarding conditions immediately before and immediately after the explosion:

I. The total momentum of the fragments is equal to the original momentum of the firecracker.

II. The total kinetic energy of the fragments is equal to the original kinetic energy of the

firecracker.

A) Statement I only B) Statement II only

C) Both Statement I and Statement II D) Neither statement is true.

35)

36) There must be equal amounts of mass on both sides of the center of mass (or center of gravity) of a

system.

A) True B) False

36)

6

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

37) What is the magnitude of the momentum of a 0.140 kg baseball traveling at 45.0 m/s? 37)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

38) A 0.14-kg baseball is dropped from rest from a height of 2.0 m above the ground. What is the

magnitude of its momentum just before it hits the ground if we neglect air resistance?

A) 0.44 kg Â· m/s

B) 0.88 kg Â· m/s

C) 0.28 kg Â· m/s

D) 1.4 kg Â· m/s

E) 0.62 kg Â· m/s

38)

39) Three objects are moving along a straight line as shown in the figure. Taking the positive direction

to be to the right, what is the total momentum of this system?

A) +14.0 kg Â· m/s

B) +106 kg Â· m/s

C) -14.0 kg Â· m/s

D) 0.00 kg Â· m/s

E) -106 kg Â· m/s

39)

40) A 0.330-kg volleyball is thrown vertically downward with a speed of 0.150 m/s in a place where g

= 9.81 m/s2. It takes it 0.0655 s to reach the ground. What is the magnitude of its momentum just

before it hits the ground?

A) 0.212 kg Â· m/s

B) 0.0216 kg Â· m/s

C) 0.163 kg Â· m/s

D) 0.262 kg Â· m/s

E) 0.0418 kg Â· m/s

40)

41) Two air track carts move along an air track towards each other. Cart A has a mass of 450 g and

moves toward the right with a speed of 0.850 m/s. Cart B has a mass of 300 g and moves toward

the left with a speed of 1.12 m/s. What is the total momentum of the two-cart system?

A) 0.719 kg Â· m/s toward the right

B) 0.047 kg Â· m/s toward the right

C) 0.750 kg Â· m/s toward the right

D) 0.750 kg Â· m/s toward the left

E) 0.719 kg Â· m/s toward the left

41)

42) A 100-g ball falls from a window that is 12 m above ground level and experiences no significant

air resistance as it falls. What is its momentum when it strikes the ground?

A) 1.8 kg Â· m/s

B) 2.4 kg Â· m/s

C) 4.8 kg Â· m/s

D) 3.3 kg Â· m/s

E) 1.5 kg Â· m/s

42)

7

43) A 0.140-kg baseball is dropped and reaches a speed of 1.20 m/s just before it hits the ground and

bounces. It rebounds with an upward velocity of 1.00 m/s. What is the change of the ball’s

momentum during the bounce?

A) 0.308 kg Â· m/s downwards

B) 0.000 kg Â· m/s

C) 0.308 kg Â· m/s upwards

D) 0.0280 kg Â· m/s downwards

E) 0.0280 kg Â· m/s upwards

43)

44) A firecracker breaks up into two pieces, one of which has a mass of 200 g and flies off along the

+x-axis with a speed of 82.0 m/s. The second piece has a mass of 300 g and flies off along the

+y-axis with a speed of 45.0 m/s. What is the total momentum of the two pieces?

A) 21.2 kg Â· m/s at 39.5Â° from the +x-axis

B) 21.2 kg Â· m/s at 56.3Â° from the +x-axis

C) 361 kg Â· m/s at 56.3Â° from the +x-axis

D) 93.5 kg Â· m/s at 28.8Â° from the +x-axis

E) 361 kg Â· m/s at 0.983Â° from the +x-axis

44)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

45) Find the magnitude and direction of the net momentum of the system shown in the figure.

Express the direction by giving the angle the net momentum makes with the +x-axis.

45)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

46) A 600-kg car makes a 90Â° turn. Its speed before the turn is 21.0 m/s and after the turn it is 24.0 m/s.

What is the magnitude of the change in the car’s momentum during the turn?

A) 12.0 Ã— 103 kgÂ·m/s

B) 22.2 Ã— 103 kgÂ·m/s

C) 10.2 Ã— 103 kgÂ·m/s

D) 19.1 Ã— 103 kgÂ·m/s

E) 9.55 Ã— 103 kgÂ·m/s

46)

47) A 0.10-kg ball, traveling horizontally at 25 m/s, strikes a wall and rebounds at 19 m/s. What is the

magnitude of the change in the momentum of the ball during the rebound?

A) 4.4 kg Â· m/s

B) 5.4 kg Â· m/s

C) 1.8 kg Â· m/s

D) 72 kg Â· m/s

E) 1.2 kg Â· m/s

47)

8

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

48) A 60-kg swimmer suddenly dives horizontally from a 150-kg raft with a speed of 1.5 m/s.

The raft is initially at rest. What is the speed of the raft immediately after the diver jumps

if the water has negligible effect on the raft?

48)

49) A 14,000-kg boxcar is coasting at 1.50 m/s along a horizontal track when it suddenly hits

and couples with a stationary 10,000-kg boxcar. What is the speed of the cars just after the

collision?

49)

50) In a police ballistics test, 2.00-g bullet traveling at 700 m/s suddenly hits and becomes

embedded in a stationary 5.00-kg wood block. What is the speed of the block immediately

after the bullet has stopped moving relative to the block?

50)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

51) A 328-kg car moving at 19.1 m/s in the +x direction hits from behind a second car moving at

13.0 m/s in the same direction. If the second car has a mass of 790 kg and a speed of 15.1 m/s right

after the collision, what is the velocity of the first car after this sudden collision?

A) -14.0 m/s B) 18.2 m/s C) 24.2 m/s D) 14.0 m/s

51)

52) A 1200-kg ore cart is rolling at 10.8 m/s across a flat friction-free surface. A crane suddenly drops

858 kg of ore vertically into the cart. How fast does the cart move just after being loaded with the

ore?

A) 4.20 m/s B) 3.80 m/s C) 5.70 m/s D) 6.30 m/s

52)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

53) An empty train car of mass 2.0 x 104 kg coasts along at 10 m/s. A 3000-kg boulder is

suddenly dropped vertically into the car. Find the speed of the car immediately after the

boulder is dropped in.

53)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

54) Two ice skaters suddenly push off against one another starting from a stationary position. The

45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60 -kg skater

acquire relative to the ice?

A) 0.75 m/s B) 0.50 m/s C) 0.00 m/s D) 0.28 m/s E) 0.38 m/s

54)

55) A 1200-kg cannon suddenly fires a 100-kg cannonball at 35 m/s.What is the recoil speed of the

cannon? Assume that frictional forces are negligible and the cannon is fired horizontally.

A) 2.9 m/s B) 3.2 m/s C) 3.5 m/s D) 35 m/s

55)

56) A dinner plate falls vertically to the floor and breaks up into three pieces, which slide horizontally

along the floor. Immediately after the impact, a 200-g piece moves along the +x-axis with a speed

of 2.00 m/s, a 235-g piece moves along the +y-axis with a speed of 1.50 m/s. The third piece has a

mass of 100 g. What is the speed of the third piece?

A) 2.57 m/s B) 2.51 m/s C) 5.33 m/s D) 3.50 m/s E) 6.83 m/s

56)

9

57) A dinner plate falls vertically to the floor and breaks up into three pieces, which slide horizontally

along the floor. Immediately after the impact, a 320-g piece moves along the +x-axis with a speed

of 2.00 m/s and a 355-g piece moves along the +y-axis with a speed of 1.50 m/s. The third piece

has a mass of 100 g. In what direction relative to the +x-axis does the third piece move?

A) 39.8Â° from the +x-axis

B) 219.8Â° from the +x-axis

C) 216.9Â° from the +x-axis

D) 36.9Â° from the +x-axis

E) 39.9Â° from the +x-axis

57)

58) In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The

bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed.

What is the speed of the block just after the bullet emerges?

A) 2.97 m/s B) 1.50 m/s C) 3.00 m/s D) 273 m/s

58)

59) Two astronauts, of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer

space. They suddenly push each other apart. What is their separation after the heavier astronaut

has moved 12 m?

A) 16 m B) 24 m C) 21 m D) 9.0 m E) 28 m

59)

60) Two astronauts, of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer

space. They suddenly push each other apart. How far has the heavier astronaut moved when the

lighter astronaut has moved 12 m?

A) 21 m B) 16 m C) 7.0 m D) 9.0 m E) 12 m

60)

61) Astronaut Jennifer’s lifeline to her spaceship comes loose and she finds herself stranded, “floating”

100 m from the mothership. She suddenly throws her 2.00-kg wrench at 20 m/s in a direction

away from the ship. If she and her spacesuit have a combined mass of 200 kg, how long does it

take her to coast back to her spaceship?

A) 500 s B) 2.50 min C) 1000 s D) 750 s E) 250 s

61)

62) A 14-cm diameter champagne bottle rests on its side on top of a frictionless horizontal table.

Suddenly, the cork pops and the bottle slides backward, covering a distance of 22.0 cm in 0.44 s. If

the mass of the bottle is 500 times the mass of the cork, find the distance from the original position

that the cork will land on the table. Neglect air resistance and assume that the cork is very small

compared to the bottle.

A) 8.5 cm B) 3000 cm C) 85 m D) 60 m

62)

10

63) The graph in the figure shows the x component F of the net force that acts for 10 s on a 100-kg

crate. What is the change in the momentum of the crate during the 10 s that this force acts?

A) -75 kg Â· m/s

B) 25 kg Â· m/s

C) 75 kg Â· m/s

D) -100 kg Â· m/s

E) -25 kg Â· m/s

63)

64) A forklift pushes a 100-kg crate, starting from rest, with a horizontal force of magnitude F. The

graph in the figure shows the x component of this force as a function of time. What is the

instantaneous velocity of the crate at time t = 10 s?

A) 25 cm/s B) -75 cm/s C) 75 cm/s D) 0.00 cm/s E) -25 cm/s

64)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

65) A batter applies an average force of 8000 N to a baseball for 1.1 ms. What is the magnitude

of the impulse delivered to the baseball by the bat?

65)

66) A batter hits a 0.140-kg baseball that was approaching him at 30 m/s and, as a result, the

ball leaves the bat at 40 m/s in the reverse of its original direction. The ball remains in

contact with the bat for 2.0 ms. What is the magnitude of the average force exerted by the

bat on the ball?

66)

67) Jennifer hits a stationary 0.20-kg ball, and it leaves her racket at 40 m/s. Time-lapse

photography shows that the ball was in contact with the racket for 40 ms.

(a) What average force did the ball exert on the racket?

(b) What is the ratio of this force to the weight of the ball?

67)

68) A 0.17-kg baseball is thrown with a speed of 38 m/s and it is hit straight back toward the

pitcher with a speed of 62 m/s. What is the magnitude of the impulse exerted upon the ball

by the bat?

68)

11

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

69) A super dart of mass 20 g, traveling at 350 m/s, strikes a steel plate at an angle of 30Â° with the plane

of the plate, as shown in the figure. It bounces off the plate at the same angle but at a speed of 320

m/s. What is the magnitude of the impulse that the plate gives to the bullet?

A) 300 N Â· s B) 0.30 N Â· s C) 0.52 N Â· s D) 6.7 N Â· s E) 4.3 N Â· s

69)

70) A golf club exerts an average horizontal force of 1000 N on a 0.045-kg golf ball that is initially at

rest on the tee. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball just

as it leaves the tee?

A) 45 m/s B) 30 m/s C) 40 m/s D) 35 m/s E) 50 m/s

70)

71) A 0.140-kg baseball is thrown with a velocity of 27.1 m/s.It is struck by the bat with an average

force of 5000 N, which results in a velocity of 37.0 m/s in the opposite direction from the original

velocity. How long were the bat and ball in contact?

A) 1.28 Ã— 10-2 s B) 4.30 Ã— 10-3 s C) 3.07 Ã— 10-2 s D) 1.79 Ã— 10-3 s

71)

72) Calculate the impulse due to a force of 4.5 N that lasts for 1.4 s.

A) 6.9 kgÂ· m/s B) 5.7 kgÂ· m/s C) 5.0 kgÂ· m/s D) 6.3 kgÂ· m/s

72)

73) A girl of mass 55 kg throws a ball of mass 0.80 kg against a wall. The ball strikes the wall

horizontally with a speed of 25 m/s, and it bounces back with this same speed. The ball is in contact

with the wall 0.050 s. What is the magnitude of the average force exerted on the wall by the ball?

A) 400 N B) 13,750 N C) 27,500 N D) 800 N E) 55,000 N

73)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

74) A 475-gram ball is traveling horizontally at 12.0 m/s to the left when it is suddenly struck

horizontally by a bat, causing it to reverse direction and initially travel at 8.50 m/s to the

right. If the bat produced an average force of 1275 N on the ball, for how long (in

milliseconds) was it in contact with the ball?

74)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

75) A 0.140 kg baseball is thrown horizontally with a velocity of 28.9 m/s. It is struck with a constant

horizontal force that lasts for 1.85 ms, which results in a velocity of 37.0 m/s in the opposite

direction. What was the magnitude of the horizontal force?

A) 2.80 kN B) 0.613 kN C) 4.99 kN D) 2.19 kN

75)

12

76) A golf ball of mass 0.050 kg is at rest on the tee. Just after being struck, it has a velocity of 102 m/s.

If the club and ball were in contact for 0.81 ms, what is the average force exerted on the ball by the

club?

A) 5.5 kN B) 4.9 kN C) 7.1 kN D) 6.3 kN

76)

77) A 0.24 kg blob of clay is thrown at a wall with an initial horizontal velocity of 16 m/s. If the clay

comes to a stop in 91 ms, what is the average horizontal force on the clay due to the wall?

A) 51 N B) 35 N C) 26 N D) 42 N

77)

78) A steady horizontal force lasting for 2.1 s gives a 1.25 kg object an acceleration of 3.2 m/s2 on a

frictionless table. What impulse does this force give to the object?

A) 11 kg Â· m/s B) 26 kg Â· m/s C) 8.4 kg Â· m/s D) 2.6 kg Â· m/s

78)

79) A block of mass m = 34 kg and speed V is behind a block of massM= 81 kg and speed of 0.50 m/s,

as shown in the figure. The surface is frictionless and the blocks collide and couple. After the

collision, the blocks have a common speed of 0.90 m/s. What is the magnitude of the impulse on

the 34-kg block due to the collision?

A) 73 N Â· s B) 41 N Â· s C) 57 N Â· s D) 14 N Â· s E) 32 N Â· s

79)

80) A very small 51-g steel ball is released from rest and falls vertically onto a steel plate. The ball

strikes the plate and is in contact with it for 0.50 ms. The ball rebounds elastically and returns to its

original height. The total time interval for a round trip is 3.00 s. What is the magnitude of the

average force exerted on the ball by the plate during contact with the plate?

A) 1500 N B) 2000 N C) 3000 N D) 3500 N E) 2490 N

80)

81) A 0.140-kg baseball is dropped from rest. It has a speed of 1.20 m/s just before it hits the ground,

and it rebounds with an upward speed of 1.00 m/s. The ball is in contact with the ground for

0.0140 s. What is the average force exerted by the ground on the ball during the time of contact?

A) 22.0 N downwards

B) 22.0 N upwards

C) 2.00 N upwards

D) 2.00 N downwards

E) 0.00 N

81)

82) A batter hits a foul ball. The 0.14-kg baseball that was approaching him at 40 m/s leaves the bat at

30 m/s in a direction perpendicular to the line between the batter and the pitcher. What is the

magnitude of the impulse delivered to the baseball?

A) 3.5 N Â· s B) 7.0 N Â· s C) 5.6 N Â· s D) 1.4 N Â· s E) 9.8 N Â· s

82)

13

83) A block of mass m = 5.6 kg, moving on a frictionless surface with a velocity of vi = 6.5 m/s to the

right, collides with a block of mass M at rest, as shown in the figure. After the collision, the 5.6-kg

block recoils with a velocity of vf = 0.70 m/s to the left. If the blocks are in contact for 0.20 s, what is

the magnitude of the average force on the 5.6-kg block, while the two blocks are in contact?

A) 202 N B) 192 N C) 0 N D) 0 N E) 182 N

83)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

84) A force of 5.3 N is needed to hold on to an umbrella in a strong wind. If the air molecules

each have a mass of 4.7 Ã—10-26 kg, and each one strikes the umbrella (without

rebounding) with a speed of 2.0 m/s in the same direction, how many atoms strike the

umbrella each second? Assume that the wind blows horizontally so that the gravity can

be neglected.

84)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

85) A fire hose is turned on the door of a burning building in order to knock the door down. This

requires a force of 1000 N. If the hose delivers 40 kg of water per second, what is the minimum

velocity of the stream needed to knock down the door, assuming the water doesn’t bounce back?

A) 30 m/s B) 25 m/s C) 15 m/s D) 20 m/s

85)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

86) A 2200-kg auto moving northward at 12.0 m/s runs into a 3800-kg truck which is also

moving northward, but at 5.00 m/s. If the vehicles lock bumpers, how fast are they moving

just after the collision?

86)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

87) A 1200-kg car moving at 15.6 m/s suddenly collides with a stationary car of mass 1500 kg. If the

two vehicles lock together, what is their combined velocity immediately after the collision?

A) 6.9 m/s B) 12.1 m/s C) 8.6 m/s D) 5.5 m/s

87)

88) A 1000-kg whale swims horizontally to the right at a speed of 6.0 m/s. It suddenly collides directly

with a stationary seal of mass 200 kg. The seal grabs onto the whale and holds fast. What is the

momentum of these two sea creatures just after their collision? You can neglect any drag effects of

the water during the collision.

A) 6000 kg Â· m/s

B) 1200 kg Â· m/s

C) 0.00 kg Â· m/s

D) 2000 kg Â· m/s

E) 7200 kg Â· m/s

88)

14

89) A 1000-kg whale swims horizontally to the right at a speed of 6.0 m/s. It suddenly collides directly

with a stationary seal of mass 200 kg. The seal grabs onto the whale and holds fast. What is the

speed of these two sea creatures just after their collision? You can neglect any drag effects of the

water during the collision.

A) 4.0 m/s B) 0.00 m/s C) 3.0 m/s D) 5.0 m/s E) 6.0 m/s

89)

90) A 2.0-kg mass moving at 5.0 m/s suddenly collides head-on with a 3.0-kg mass at rest. If the

collision is perfectly inelastic, what is the speed of the masses just after the collision?

A) 2.0 m/s B) 2.5 m/s

C) 10 m/s D) 0 m/s, since the collision is inelastic

90)

91) A block of mass m = 4.4 kg, moving on frictionless surface with a speed vi = 9.2 m/s, makes a

sudden perfectly elastic collision with a second block of mass M, as shown in the figure. The

second block is originally at rest. Just after the collision, the 4.4-kg block recoils with a speed of

vf = 2.5 m/s. What is the mass M of the second block?

A) 0 kg B) 0 kg C) 0 kg D) 7.7 kg E) 0 kg

91)

92) A block of mass m = 3.6 kg, moving on a frictionless surface with a speed vi = 9.3 m/s, makes a

sudden perfectly elastic collision with a stationary block of mass M, as shown in the figure. Just

after the collision, the 3.6-kg block recoils with a speed of vf = 2.7 m/s.What is the speed V of the

other block?

A) 6.6 m/s B) 12.0 m/s C) 8.0 m/s D) 10.7 m/s E) 9.3 m/s

92)

93) A 320-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 270-g

cart. What is the speed of the 270-g cart just after the collision?

A) 0.106 m/s B) 2.72 m/s C) 1.36 m/s D) 0.678 m/s E) 1.14 m/s

93)

94) A 320-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 270-g

cart. What is the speed of the 320-g cart just after the collision?

A) 0.11 m/s B) 1.4 m/s C) 0.21 m/s D) 1.1 m/s E) 0.68 m/s

94)

95) A 550-g ball traveling at 8.0 m/s undergoes a sudden head-on elastic collision with a 250-g ball

traveling toward it also at 8.0 m/s. What is the speed of the 250-g mass just after the collision?

A) 0 m/s B) 14 m/s C) 4.0 m/s D) 15 m/s E) 8.0 m/s

95)

15

96) A 340-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 300-g

cart. What is the speed of the 300-g cart just after the collision?

A) 0.664 m/s

B) 0.0781 m/s

C) 0.625 m/s

D) 1.25 m/s

E) 1.33 m/s

96)

97) A proton of mass m is at rest when it is suddenly struck head-on by an alpha particle (which

consists of 2 protons and 2 neutrons) moving at speed v. If the collision is perfectly elastic, what

speed will the alpha particle have after the collision? (Assume the neutron’s mass is equal to the

proton’s mass.)

A) 2v/3 B) 3v/5 C) zero D) 5v/3

97)

98) A 50-g ball moving at 10 m/s in the +x direction suddenly collides head-on with a stationary ball

of mass 100 g. If the collision is perfectly elastic, what is the velocity of each ball immediately after

the collision?

A) -3.3 m/s, +6.7 m/s B) +6.7 m/s, -3.3 m/s

C) -6.7 m/s, +3.3 m/s D) +3.3 m/s, -6.7 m/s

98)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

99) In a perfectly elastic collision, a 400-g ball moving toward the east at 3.7 m/s suddenly

collides head-on with a 200 g ball sitting at rest.

(a) Determine the velocity of the first ball just after the collision.

(b) Determine the velocity of the second ball just after the collision.

(c) Is kinetic energy conserved in this collision? How do you know?

99)

100) An 80-kg man is skating northward and happens to suddenly collide with a 20-kg boy

who is ice skating toward the east. Immediately after the collision, the man and boy are

seen to be moving together at 2.5 m/s in a direction 60Â° north of east. How fast was the

boy moving just before the collision?

100)

101) A car (of mass 1500 kg) and a small truck (of mass 2000 kg) collide suddenly at right

angles at an icy intersection. The car was originally traveling eastward at 20.0 m/s and the

truck was traveling northward at 20.0 m/s just before the collision took place. What is the

speed of the combined wreck just after the collision if the vehicles become enmeshed?

101)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

102) Two vehicles approach a right angle intersection and then suddenly collide. After the collision,

they become entangled. If their mass ratios were 1:4 and their respective speeds as they

approached the intersection were both 13 m/s, find the magnitude and direction of the final

velocity of the wreck.

A) 16 m/s at 14Â° with respect to the original direction of the lighter car

B) 11 m/s at 14Â° with respect to the original direction of the lighter car

C) 26 m/s at 76Â° with respect to the original direction of the lighter car

D) 16 m/s at 76Â° with respect to the original direction of the lighter car

E) 11 m/s at 76Â° with respect to the original direction of the lighter car

102)

16

103) A car heading north suddenly collides at an intersection with a truck of the same mass heading

east. If they lock together and travel at 28 m/s at 15Â° north of east just after the collision, how fast

was the car initially traveling?

A) 28 m/s B) 14 m/s C) 7 m/s D) 11 m/s

103)

104) A puck with a mass m1 = 50 g moving at 1.0 m/s approaches a stationary puck with a mass m2 =

100 g on a frictionless air table, and they undergo a sudden two-dimensional elastic collision. After

the collision, both pucks have identical speeds, but travel in different directions. What is the angle

between the original and final paths of puck with mass m1?

A) 60Â° B) 150Â° C) 90Â° D) 120Â° E) 30Â°

104)

105) A 900-kg car traveling east at 15.0 m/s suddenly collides with a 750-kg car traveling north at 20.0

m/s. The cars stick together after the collision. What is the speed of the wreckage just after the

collision?

A) 35.0 m/s B) 12.2 m/s C) 25.0 m/s D) 17.3 m/s E) 6.10 m/s

105)

106) A 900-kg car traveling east at 15.0 m/s suddenly collides with a 750-kg car traveling north at 20.0

m/s. The cars stick together after the collision. In what direction does the wreckage move just after

the collision?

A) 45.0Â° N of E

B) 53.1Â° N of E

C) 42.0Â° N of E

D) 36.9Â° N of E

E) 48.0Â° N of E

106)

107) A 900-kg car traveling 30.0Â° south of east at 12.0 m/s suddenly collides with a 750-kg car traveling

north at 17.0 m/s. The cars stick together after colliding. What is the speed of the wreckage just

after the collision?

A) 25.0 m/s B) 12.2 m/s C) 17.3 m/s D) 20.4 m/s E) 7.21 m/s

107)

108) A 1500-kg car traveling at 90 km/h toward the east suddenly collides with a 3000-kg car traveling

at 60 km/h toward the south. The two cars stick together after the collision. What is the speed of

the cars after collision?

A) 14 m/s B) 22 m/s C) 8.3 m/s D) 17 m/s

108)

109) A 1500-kg car traveling at 90 km/h toward the east suddenly collides with a 3000-kg car traveling

at 60 km/h toward the south. The two cars stick together after the collision. What is the direction of

motion of the cars after collision?

A) 53.1Â° E of S B) 53.1Â° S of E C) 36.9Â° E of S D) 36.9Â° S of E

109)

110) Two dogs, Rover and Fido, run on a level frictionless surface. Rover runs eastward with a

momentum of 24 kg . m/s, and Fido runs northward with momentum 10 kg . m/s. They make a

sudden perfectly inelastic collision. What is the magnitude of their combined momentum after the

collision?

A) 34 kg . m/s

B) 14 kg . m/s

C) 26 kg . m/s

D) It cannot be determined without knowing the masses and velocities of the dogs.

110)

17

111) A 0.140-kg baseball is dropped from rest from a height of 2.20 m above the ground and

experiences negligible air resistance as it falls. It rebounds to a height of 1.60 m. What change in the

ball’s momentum occurs as it rebounds from the ground?

A) 0.117 kg Â· m/s upwards

B) 0.350 kg Â· m/s downwards

C) 0.117 kg Â· m/s downwards

D) 0.350 kg Â· m/s upwards

E) 1.70 kg Â· m/s upwards

111)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

112) A 0.32-kg ball is moving horizontally at 30 m/s just before suddenly bouncing off a wall

Just after the bounce, it is moving horizontally at 25 m/s but in the opposite direction.

(a) What is the magnitude of the change in momentum of the ball during the bounce?

(b) What percentage of the ball’s original kinetic energy was lost in the collision?

112)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

113) In a police ballistics test, a 2.00-g bullet suddenly hits and becomes embedded in a 5.00-kg wood

block which is hanging from a 1.20-m long string. This causes the block to swing through an arc of

3.50Â°. What was the speed of the bullet just before it hit the block?

A) 789 m/s B) 524 m/s C) 262 m/s D) 16.7 m/s E) 25.3 m/s

113)

114) A block of mass m = 9.0 kg and speed V and is behind a block of mass M= 27 kg and speed of

0.50 m/s, as shown int the figure. The surface is frictionless, and the blocks suddenly collide and

couple. After the collision, the blocks have a common speed of 0.90 m/s. How much kinetic energy

of the blocks is lost due to the collision?

A) 4.6 J B) 2.0 J C) 11 J D) 8.6 J E) 31 J

114)

115) As shown in the figure, a bullet of mass 0.010 kg moving horizontally suddenly strikes a block of

wood of mass 1.5 kg that is suspended as a pendulum. The bullet lodges in the wood, and together

they swing upward a vertical distance of 0.40 m. The length of the string is 2.0 m. What was the

speed of the bullet just before it struck the wooden block?

A) 420 m/s B) 650 m/s C) 250 m/s D) 67 m/s E) 370 m/s

115)

18

116) An 8.0-g bullet is suddenly shot into a 4.0-kg block that is at rest on a frictionless horizontal

surface, as shown in the figure. The bullet remains lodged in the block. The block then moves

against a spring and compresses it by 3.7 cm. The force constant (spring constant) of the spring is

2500 N/m. What was the initial speed v of the bullet?

A) 520 m/s B) 440 m/s C) 500 m/s D) 480 m/s E) 460 m/s

116)

117) An 8.0-g bullet is suddenly shot into a 4.0-kg block, at rest on a frictionless horizontal surface, as

shown in the figure. The bullet remains lodged in the block. The block then moves against a spring

and compresses it by 8.9 cm. The force constant (spring constant) of the spring is 1400 N/m. What

is the magnitude of the impulse on the block (including the bullet inside) due to the spring during

the entire time interval during which the block compresses the spring?

A) 12 N Â· s B) 6.7 N Â· s C) 8.3 N Â· s D) 10 N Â· s E) 13 N Â· s

117)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

118) In a police rifle test, a 15-g bullet traveling 213 m/s in a vertical direction suddenly buries

itself in a 2.4-kg block of wood at rest directly above it. As a result, the bullet-block

combination moves vertically upward.

(a) Determine the velocity of the bullet-block combination just after the impact.

(b) Determine the maximum height reached by the bullet/block combination.

(c) Is kinetic energy conserved in this collision?

118)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

119) In a certain nuclear reactor, neutrons suddenly collide with deuterons, which have twice the mass

of neutrons. In a head-on elastic collision with a stationary deuteron, what fraction of the initial

kinetic energy of a neutron is transferred to the deuteron?

A) 1/3 B) 5/6 C) 8/9 D) 3/4 E) 1/2

119)

120) In a certain nuclear reactor, neutrons suddenly collide with carbon nuclei, which have 12 times the

mass of neutrons. In a head-on elastic collision with a stationary carbon nucleus, what fraction of

its initial speed does the neutron have after the collision?

A) 10/13 B) 1/12 C) 11/13 D) 11/12 E) 5/6

120)

121) An object initially at rest suddenly explodes in two fragments of masses 2.6 kg and 3.3 kg that

move in opposite directions. If the speed of the first fragment is 3.6 m/s, find the internal energy of

the explosion.

A) 30 kJ B) 38 kJ C) 30 J D) 38 J

121)

19

122) Two simple pendulums of equal length l = 0.45 m are suspended from the same point. The

pendulum bobs are small solid steel spheres. The first bob is drawn back to make a 35Â° angle with

the vertical, while the other one is left hanging at rest. If the first bob has a mass of 0.25 kg and the

second has a mass of 0.54 kg, how high will the second bob rise above its initial position when

struck elastically by the first bob after it is released?

A) 3.3 cm B) 3.9 cm C) 2.7 cm D) 4.4 cm

122)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

123) On a frictionless horizontal surface, a 1.50-kg mass traveling at 3.50 m/s suddenly collides

with and sticks to a 3.00-kg mass that is initially at rest, as shown in the figure. This

system then runs into an ideal spring of force constant (spring constant) 50.0 N/cm.

(a) What will be the maximum compression distance of the spring?

(b) How much mechanical energy is lost during this process? During which parts of the

process (the collision and compression of the spring) is this energy lost?

123)

124) A baseball pitcher is employing a ballistic pendulum to determine the speed of his fastball.

A 3.3-kg lump of clay is suspended from a cord 2.0 m long. When the pitcher throws his

fastball aimed directly at the clay, the ball suddenly becomes embedded in the clay and

the two swing up to a maximum height of 0.080 m. If the mass of the baseball is 0.21 kg,

find the speed of the pitched ball.

124)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

125) A 1200-kg pick-up truck traveling south at 15 m/s suddenly collides with a 750-kg car that is

traveling east. The two vehicles stick together and slide along the road after colliding. A highway

patrol officer investigating the accident determines that the final position of the wreckage after the

collision is 25 m, at an angle of 50Â° south of east, from the point of impact. She also determines that

the coefficient of kinetic friction between the tires and the road at that location was 0.40. What was

the speed of the car just before the collision?

A) 23 m/s B) 20 m/s C) 17 m/s D) 4.8 m/s E) 14 m/s

125)

20

126) In the figure, four point masses are placed as shown. Assume that all the numbers in the figure are

accurate to two significant figures. What are the x and y coordinates of the center of mass (or center

of gravity) of this arrangement?

A) (2.2 m, 2.6 m)

B) (2.3 m, 2.8 m)

C) (2.3 m, 2.7 m)

D) (2.3 m, 2.6 m)

E) (2.2 m, 2.7 m)

126)

127) As shown in the figure, a 60-cm length of uniform wire, of mass 60 g, is bent into a right triangle.

What are the x and y coordinates of the center of mass (or center of gravity) of this triangle?

A) (9.0 cm, 4.0 cm)

B) (10 cm, 3.0 cm)

C) (8.0 cm, 5.0 cm)

D) (10 cm, 5.0 cm)

E) (8.0 cm, 3.0 cm)

127)

128) A 60.0-kg man stands at one end of a 20.0-kg uniform 10.0-m long board. How far from the man

is the center of mass (or center of gravity) of the man-board system?

A) 5.00 m B) 9.00 m C) 1.25 m D) 7.50 m E) 2.50 m

128)

129) A 2.0-m rope is lying on a table. You pick up one end and start raising it vertically. How high

above the table is the center of mass (or center of gravity) of the rope when half of the rope has

lifted off the table?

A) 0.75 m B) 1.0 m C) 1.5 m D) 0.50 m E) 0.25 m

129)

130) Three masses are located in the x-y plane as follows: a mass of 6 kg is at (0 m, 0 m), a mass of 4 kg

is at (3 m, 0 m), and a mass of 2 kg is at (0 m, 3 m). Where is the center of mass (or center of

gravity) of the system?

A) (1 m, 2 m)

B) (1 m, 1 m)

C) (0.5 m, 1 m)

D) (1 m, 0.5 m)

E) (2 m, 1 m)

130)

21

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

131) Three balls are moving along a straight line having the instantaneous positions shown in

the figure. At that instant, find the location and velocity of the center of mass (or center of

gravity) of this system.

131)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

132) A 30-kg child stands at one end of a floating 20-kg canoe that is 5.0-m long and initially at rest in

the water. The child then slowly walks to the other end of the canoe. How far does the canoe move

in the water, assuming water friction is negligible?

A) 3.0 m B) 1.0 m C) 5.0 m D) 4.0 m E) 2.0 m

132)

133) The center of mass (or center of gravity) of a two-particle system is at the origin. One particle is

located at (3.0 m, 0.0 m) and has a mass of 2.0 kg. The other particle has a mass of 3.0 kg. What is

the location of the 3.0-kg particle?

A) (3.0 m, 0.0 m) B) (-3.0 m, 0.0 m) C) (-2.0 m, 0.0 m) D) (2.0 m, 0.0 m)

133)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

134) Three small masses are positioned at the following coordinates: 3.0 kg at (3.0 m, 2.0 m); 4.0

kg at (0.0 m, -1.0 m); and 5.0 kg at (5.0 m, -7.0 m). What are the coordinates of the center

of mass (or center of gravity) of this system?

134)

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

135) Three small masses are positioned as follows: 2.0 kg at (0.0 m, 0.0 m), 2.0 kg at (2.0 m, 0.0 m), and

4.0 kg at (2.0 m, 1.0 m). Determine the coordinates of the center of mass (or center of gravity) of

this system.

A) (1.5 m, 0.50 m) B) (0.50 m, 1.5 m) C) (2.5 m, 1.5 m) D) (2.5 m, 0.50 m)

135)

136) Three masses, 1.0 kg, 2.0 kg, and 3.0 kg, are located at (0.0 m, 0.0 m), (1.0 m, 1.0 m), and (2.0 m,

-2.0 m), respectively. What is the location of the center of mass (or center of gravity) of this system?

A) (1.3 m, 0.67 m) B) (1.3 m, -0.67 m)

C) (-1.3 m, -0.67 m) D) (-1.3 m, 0.67 m)

136)

137) A 3.0-kg mass is located at (0.0 m, 8.0 m), and a 1.0-kg mass is located at (12 m, 0.0 m). You want

to add a 4.0-kg mass so that the center of mass (or center of gravity) of the three-mass system will

be at the origin. What should be the coordinates of the 4.0-kg mass?

A) (-6.0 m, -3.0 m) B) (-12 m, -8.0 m)

C) (-3.0 m, -6.0 m) D) (3.0 m, 6.0 m)

137)

SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.

138) A 1.0-g bead is at (-2.0 cm, 2.0 cm), a 2.0-g bead is at (2.0 cm, -4.0 cm), and a 3.0-g bead

is at (2.0 cm, 0.0 cm). What are the coordinates of the center of mass (or center of gravity)

of this system of beads?

138)

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139) Consider the sun and its largest planet Jupiter. On the line joining them, how far from the

center of the sun is their center mass? Is it within or outside the sun? (Jupiter-sun distance

is 778 Ã— 106 km, diameter of the sun is 1.4 Ã— 106 km, the sun is 1000 times as massive as

Jupiter)

139)

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Answer Key

Testname: UNTITLED7

1) B

2) B, E

3) D

4) C

5) A

6) B

7) B

8) A

9) C

10) A

11) B

12) C, D

13) A

14) B

15) C

16) A

17) A

18) E

19) B

20) B, C

21) A

22) C

23) E

24) B

25) D

26) E

27) B, C

28) A

29) B

30) D

31) B

32) A

33) E

34) E

35) A

36) B

37) 6.30 kg Â· m/s

38) B

39) C

40) D

41) B

42) E

43) C

44) A

45) 123 kg . m/s , 212Â°

46) D

47) A

48) 0.60 m/s

49) 0.875 m/s

50) 0.280 m/s

24

Answer Key

Testname: UNTITLED7

51) D

52) D

53) 8.7 m/s

54) D

55) A

56) C

57) B

58) B

59) E

60) D

61) A

62) B

63) A

64) B

65) 8.8 N Â· s

66) 4900 N

67) (a) 0.20 kN (b) 100

68) 17 N Â· s

69) D

70) C

71) D

72) D

73) D

74) 7.64 ms

75) C

76) D

77) D

78) C

79) E

80) C

81) B

82) B

83) A

84) 5.6 Ã—1025 per second

85) B

86) 7.57 m/s

87) A

88) A

89) D

90) A

91) D

92) A

93) C

94) A

95) B

96) E

97) B

98) A

99) (a) 1.2 m/s toward the east (b) 4.9 m/s toward the east (c) Yes, it is an elastic collision.

100) 6.3 m/s

25

Answer Key

Testname: UNTITLED7

101) 14.3 m/s

102) E

103) B

104) C

105) B

106) E

107) E

108) A

109) B

110) C

111) E

112) (a) 18 N Â· s (b) 31%

113) B

114) D

115) A

116) E

117) E

118) (a) 1.3 m/s (b) 0.089 m (c) No, this is an inelastic collision.

119) C

120) C

121) C

122) A

123) (a) 3.50 cm, (b) 6.13 J during the inelastic collision

124) 21 m/s

125) A

126) B

127) B

128) C

129) E

130) D

131) 7.00 m to the right of the 2.00 kg ball, 1.11 m/s to the right

132) A

133) C

134) (2.8 m, -2.8 m)

135) A

136) B

137) C

138) 1.3 cm, -1.0 cm

139) 0.78 Ã— 106 km from the center of the sun, just outside the solar surface

26