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#### PERSONAL FINANCE CANADIAN 6TH EDITION BY KAPOOR – TEST BANK

**Chapter 6â€”Circular Motion and Other Applications of Newton’s Laws**

**MULTIPLE CHOICE**

- A race car travels 40 m/s around a banked (45Â° with the horizontal) circular (radius = 0.20 km) track. What is the magnitude of the resultant force on the 80-kg driver of this car?

a. | 0.68 kN |

b. | 0.64 kN |

c. | 0.72 kN |

d. | 0.76 kN |

e. | 0.52 kN |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- An airplane travels 80 m/s as it makes a horizontal circular turn which has a 0.80-km radius. What is the magnitude of the resultant force on the 75-kg pilot of this airplane?

a. | 0.69 kN |

b. | 0.63 kN |

c. | 0.66 kN |

d. | 0.60 kN |

e. | 0.57 kN |

ANS:Â DÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- An airplane moves 140 m/s as it travels around a vertical circular loop which has a 1.0-km radius. What is the magnitude of the resultant force on the 70-kg pilot of this plane at the bottom of this loop?

a. | 2.1 kN |

b. | 1.4 kN |

c. | 0.69 kN |

d. | 1.5 kN |

e. | 1.3 kN |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A car travels along the perimeter of a vertical circle (radius = 0.25 km) at a constant speed of 30 m/s. What is the magnitude of the resultant force on the 60-kg driver of the car at the lowest point on this circular path?

a. | 0.37 kN |

b. | 0.80 kN |

c. | 0.22 kN |

d. | 0.59 kN |

e. | 0.45 kN |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A 30-kg child rides on a circus Ferris wheel that takes her around a vertical circular path with a radius of 20 m every 22 s. What is the magnitude of the resultant force on the child at the highest point on this trajectory?

a. | 49 N |

b. | 0.29 kN |

c. | 0.34 kN |

d. | 0.25 kN |

e. | 0.76 kN |

ANS:Â AÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- An amusement ride consists of a car moving in a vertical circle on the end of a rigid boom. The radius of the circle is 10 m. The combined weight of the car and riders is 5.0 kN. At the top of the circle the car has a speed of 5.0 m/s which is not changing at that instant. What is the force of the boom on the car at the top of the circle?

a. | 3.7 kN down |

b. | 1.3 kN down |

c. | 6.3 kN up |

d. | 3.7 kN up |

e. | 5.2 kN down |

ANS:Â DÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A highway curve has a radius of 0.14 km and is unbanked. A car weighing 12 kN goes around the curve at a speed of 24 m/s without slipping. What is the magnitude of the horizontal force of the road on the car?

a. | 12 kN |

b. | 17 kN |

c. | 13 kN |

d. | 5.0 kN |

e. | 49 kN |

ANS:Â DÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A 4.0-kg mass on the end of a string rotates in a circular motion on a horizontal frictionless table. The mass has a constant speed of 2.0 m/s and the radius of the circle is 0.80 m. What is the magnitude of the resultant force acting on the mass?

a. | 39 N |

b. | 20 N |

c. | 44 N |

d. | 0 N |

e. | 30 N |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A stunt pilot weighing 0.70 kN performs a vertical circular dive of radius 0.80 km. At the bottom of the dive, the pilot has a speed of 0.20 km/s which at that instant is not changing. What force does the plane exert on the pilot?

a. | 3.6 kN up |

b. | 4.3 kN up |

c. | 2.9 kN down |

d. | 2.9 kN up |

e. | 5.8 kN down |

- A car travels around an unbanked highway curve (radius 0.15 km) at a constant speed of 25 m/s. What is the magnitude of the resultant force acting on the driver, who weighs 0.80 kN?

a. | 0.87 kN |

b. | 0.34 kN |

c. | 0.80 kN |

d. | 0.00 kN |

e. | 0.67 kN |

- A 0.50-kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m). When the mass is at the lowest point on the circle, the speed of the mass is 12 m/s. What is the magnitude of the force of the string on the mass at this position?

a. | 31 N |

b. | 36 N |

c. | 41 N |

d. | 46 N |

e. | 23 N |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A roller-coaster car has a mass of 500 kg when fully loaded with passengers. The car passes over a hill of radius 15 m, as shown. At the top of the hill, the car has a speed of 8.0 m/s. What is the force of the track on the car at the top of the hill?

a. | 7.0 kN up |

b. | 7.0 kN down |

c. | 2.8 kN down |

d. | 2.8 kN up |

e. | 5.6 kN down |

- A 0.20-kg object attached to the end of a string swings in a vertical circle (radius = 80 cm). At the top of the circle the speed of the object is 4.5 m/s. What is the magnitude of the tension in the string at this position?

a. | 7.0 N |

b. | 2.0 N |

c. | 3.1 N |

d. | 5.1 N |

e. | 6.6 N |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A roller-coaster car has a mass of 500 kg when fully loaded with passengers. At the bottom of a circular dip of radius 40 m (as shown in the figure) the car has a speed of 16 m/s. What is the magnitude of the force of the track on the car at the bottom of the dip?

a. | 3.2 kN |

b. | 8.1 kN |

c. | 4.9 kN |

d. | 1.7 kN |

e. | 5.3 kN |

- A 0.50 kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m). When the mass is at the highest point of the circle the speed of the mass is 8.0 m/s. What is the magnitude of the force of the string on the mass at this position?

a. | 21 N |

b. | 11 N |

c. | 16 N |

d. | 26 N |

e. | 36 N |

- A 50-kg child riding a Ferris wheel (radius = 10 m) travels in a vertical circle. The wheel completes one revolution every 10 s. What is the magnitude of the force on the child by the seat at the highest point on the circular path?

a. | 0.29 kN |

b. | 0.49 kN |

c. | 0.69 kN |

d. | 0.20 kN |

e. | 0.40 kN |

ANS:Â AÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A 0.30-kg mass attached to the end of a string swings in a vertical circle (
*R*= 1.6 m), as shown. At an instant when*q*= 50Â°, the tension in the string is 8.0 N. What is the magnitude of the resultant force on the mass at this instant?

a. | 5.6 N |

b. | 6.0 N |

c. | 6.5 N |

d. | 5.1 N |

e. | 2.2 N |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- An object attached to the end of a string swings in a vertical circle (
*R*= 1.2 m), as shown. At an instant when*q*= 30Â°, the speed of the object is 5.1 m/s and the tension in the string has a magnitude of 20 N. What is the mass of the object?

a. | 2.0 kg |

b. | 1.5 kg |

c. | 1.8 kg |

d. | 1.2 kg |

e. | 0.80 kg |

ANS:Â DÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- A 0.40-kg mass attached to the end of a string swings in a vertical circle having a radius of 1.8 m. At an instant when the string makes an angle of 40 degrees below the horizontal, the speed of the mass is 5.0 m/s. What is the magnitude of the tension in the string at this instant?

a. | 9.5 N |

b. | 3.0 N |

c. | 8.1 N |

d. | 5.6 N |

e. | 4.7 N |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- A 0.50-kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m). When the string is horizontal, the speed of the mass is 8.0 m/s. What is the magnitude of the force of the string on the mass at this position?

a. | 16 N |

b. | 17 N |

c. | 21 N |

d. | 11 N |

e. | 25 N |

ANS:Â AÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A 4.0-kg mass attached to the end of a string swings in a vertical circle of radius 2.0 m. When the string makes an angle of 35Â° with the vertical as shown, the speed of the mass is 5.0 m/s. At this instant what is the magnitude of the force the string exerts on the mass?

a. | 50 N |

b. | 82 N |

c. | 89 N |

d. | 11 N |

e. | 61 N |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- A split highway has a number of lanes for traffic. For traffic going in one direction, the radius for the inside of the curve is half the radius for the outside. One car, car A, travels on the inside while another car of equal mass, car B, travels at equal speed on the outside of the curve. Which statement about resultant forces on the cars is correct?

a. | The force on A is half the force on B. |

b. | The force on B is half the force on A. |

c. | The force on A is four times the force on B. |

d. | The force on B is four times the force on A. |

e. | There is no net resultant force on either as long as they stay on the road while turning. |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- A race car traveling at 100 m/s enters an unbanked turn of 400 m radius. The coefficient of (static) friction between the tires and the track is 1.1. The track has both an inner and an outer wall. Which statement is correct?

a. | The race car will crash into the outer wall. |

b. | The race car will crash into the inner wall. |

c. | The car will stay in the center of the track. |

d. | The car will stay in the center of the track if the driver speeds up. |

e. | The car would stay in the center of the track if the radius were reduced to 200 m. |

- A student is sitting on the right side of a school bus when it makes a right turn. We know that the force of gravity acts downwards and a normal force from the seat acts upwards. If the student stays in place when the bus turns, we also know that there must be

a. | no other force on the student. |

b. | a force parallel to the seat directed forward on the student. |

c. | a force parallel to the seat directed to the left on the student. |

d. | a force parallel to the seat directed to the right on the student. |

e. | a force parallel to the seat in a direction between forward and left on the student. |

ANS:Â DÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- For a plane to be able to fly clockwise in a horizontal circle as seen from above, in addition to exerting a force downwards on the air

a. | it must be increasing its speed. |

b. | it must exert a force on the air that is directed to the plane’s left side. |

c. | it must exert a force on the air that is directed to the plane’s right side. |

d. | it does not need to exert a force: it must only move the wing flaps out. |

e. | it only needs to deflect the air without exerting any additional force on the air. |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- When a car goes around a circular curve on a level road without slipping,

a. | no frictional force is needed because the car simply follows the road. |

b. | the frictional force of the road on the car increases when the car’s speed decreases. |

c. | the frictional force of the road on the car increases when the car’s speed increases. |

d. | the frictional force of the road on the car increases when the car moves to the outside of the curve. |

e. | there is no net frictional force because the road and the car exert equal and opposite forces on each other. |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- An iceboat is traveling in a circle on the ice. Halfway around the circle the sail and the steering mechanism fall off the boat. Which statement is correct?

a. | The boat will continue traveling in the circle because there is no friction. |

b. | The boat will continue to travel in the circle because its velocity exerts a force on it. |

c. | The boat will move off on a line tangent to the circle because there is no force on it. |

d. | The boat will move off tangent to the circle because there is a force on it perpendicular to the boat directed to the outside of the circle. |

e. | The boat will move off to the outside perpendicular to the tangent line since a force directed to the outside of the circle always acts on the boat. |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- A rock attached to a string swings in a vertical circle. Which free body diagram could correctly describe the force(s) on the rock when it is at the highest point?

a. | b. | c. | d. | e. |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- A rock attached to a string swings in a vertical circle. Which free body diagram could correctly describe the force(s) on the rock when the string is in one possible horizontal position?

a. | c. | e. | |||

b. | d. |

- A rock attached to a string swings in a vertical circle. Which free body diagram could correctly describe the force(s) on the rock when it is at the lowest point?

a. | b. | c. | d. | e. |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- Two small cylindrical plastic containers with flat bottoms are placed on a turntable that has a smooth flat surface. Canister A is empty; canister B contains lead shot. Each canister is the same distance
*r*from the center. The coefficient of static friction between the canisters and the turntable is*m*_{s}. When the speed of the turntable is gradually increased,

a. | only the lighter container slides outward off the turntable; the heavier one stays on. |

b. | only the heavier container slides outward off the turntable; the lighter one stays on. |

c. | both containers slide off the turntable at the same turntable speed. |

d. | the lighter container slides inward. |

e. | the heavier container slides inward. |

- A hornet circles around a pop can at constant speed once per second in a path with a 12-cm diameter. We can conclude that the hornet’s wings must push on the air with force components that are

a. | straight down. |

b. | down and inwards. |

c. | down and outwards. |

d. | down and backwards. |

e. | down, inwards and backwards. |

- A hornet circles around a pop can at increasing speed while flying in a path with a 12-cm diameter. We can conclude that the hornet’s wings must push on the air with force components that are

a. | straight down. |

b. | down and inwards. |

c. | down and outwards. |

d. | down and backwards. |

e. | down, backwards and outwards. |

ANS:Â EÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- Frank says that if you release the string when swinging a ball in a horizontal circle, the ball flies out in the radial direction defined by the string at the instant you release the ball. John says that it flies out along a tangent line perpendicular to the string, and that it then drops straight down to the ground. Which one, if either, is correct?

a. | Frank, because the centrifugal force is no longer counteracted by the string. |

b. | Frank, because balls naturally fly straight out. |

c. | John, because there is no centrifugal force. |

d. | John, because balls fall straight down when released. |

e. | Neither, because although there is no centrifugal force, and the ball’s velocity is tangent to the circle at the instant of release, the ball then follows a parabolic trajectory. |

ANS:Â EÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- The equation below is the solution to a problem.

.

The best physical representation of this equation is

a. | a sphere of 2.00 kg mass under a 6.00 N tension when at the bottom of a vertical circle. |

b. | a sphere of 2.00 kg mass under a 6.00 N tension when at the side of a vertical circle. |

c. | a sphere of 2.00 kg mass under a 6.00 N tension when at the top of a vertical circle. |

d. | a sphere of 2.00 kg mass at any point on a horizontal circle. |

e. | a 2.00 kg gecko running on the ceiling with a speed of 8.00 m/s. |

- The equation below is the solution to a problem.

.

The best physical representation of this equation is

a. | a sphere of 2.00 kg mass under a 45.2 N tension when at the bottom of a vertical circle. |

b. | a sphere of 2.00 kg mass under a 45.2 N tension when at the side of a vertical circle. |

c. | a sphere of 2.00 kg mass under a 45.2 N tension when at the top of a vertical circle. |

d. | a sphere of 2.00 kg mass at any point on a horizontal circle. |

e. | a 2.00 kg gecko running on the ceiling with a speed of 8.00 m/s. |

- The equation below is the solution to a problem.

.

The best physical representation of this equation is

a. | a sphere of 2.00 kg mass under a 25.6 N tension when at the bottom of a vertical circle. |

b. | a sphere of 2.00 kg mass under a 25.6 N tension when at the side of a vertical circle. |

c. | a sphere of 2.00 kg mass under a 25.6 N tension when at the top of a vertical circle. |

d. | a sphere of 2.00 kg mass at any point on a horizontal circle. |

e. | a 2.00 kg gecko running on the ceiling with a speed of 8.00 m/s. |

- The coefficient of static friction for the tires of a race car is 0.950 and the coefficient of kinetic friction is 0.800. The car is on a level circular track of 50.0 m radius on a planet where Â compared to Earth’s . The maximum safe speed on the track on the planet is ____ times as large as the maximum safe speed on Earth.

a. | 0.250 |

b. | 0.500 |

c. | 1.00 |

d. | 2.00 |

e. | 4.00 |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- The coefficient of static friction for the tires of a race car is 0.950 and the coefficient of kinetic friction is 0.800. The car is on a level circular track of 50.0 m radius on a planet where Â compared to Earth’s . If the car is to be able to travel at the same speed on the planet as on Earth, the radius of the track on the planet must be ____ times as large as the radius of the track on Earth.

a. | 0.250 |

b. | 0.500 |

c. | 1.00 |

d. | 2.00 |

e. | 4.00 |

ANS:Â EÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- A boy on board a cruise ship drops a 30.0 gm marble into the ocean. If the resistive force proportionality constant is 0.500 kg/s, what is the terminal speed of the marble in m/s?

a. | 0.147 |

b. | 0.294 |

c. | 0.588 |

d. | 1.18 |

e. | 2.35 |

- A skydiver of 75 kg mass has a terminal velocity of 60 m/s. At what speed is the resistive force on the skydiver half that when at terminal speed?

a. | 15 m/s |

b. | 49 m/s |

c. | 30 m/s |

d. | 42 m/s |

e. | 36 m/s |

- The following equation was obtained by solving a physics problem:

The best physical representation of the situation is

a. | A car traveling at 16.0 m/s is 19.2Â° into a turn of a quarter circle on a level road. |

b. | A mass on a string that is originally horizontal has fallen to where the angle between the string and the vertical direction is 19.2Â°. |

c. | A mass on a string originally horizontal has fallen 19.2Â° from the horizontal direction. |

d. | A car traveling at 16.0 m/s is on a circular curve banked at 19.2Â°. |

e. | A car traveling at 16.0 m/s and going over a semicircular mountain-top road is 19.2Â° down from the top. |

ANS:Â DÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- An airplane flies in a horizontal circle of radius 500 m at a speed of 150 m/s. If the plane were to fly in the same 500 m circle at a speed of 300 m/s, by what factor would its centripetal acceleration change?

a. | 0.25 |

b. | 0.50 |

c. | 1.00 |

d. | 2.00 |

e. | 4.00 |

ANS:Â EÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- An airplane flies in a horizontal circle of radius 500 m at a speed of 150 m/s. If the radius were changed to 1 000 m, but the speed remained the same, by what factor would its centripetal acceleration change?

a. | 0.25 |

b. | 0.50 |

c. | 1.00 |

d. | 2.00 |

e. | 4.00 |

- An airplane flies in a horizontal circle of radius 500 m at a speed of 150 m/s. If the plane were to fly in the same 1 000 m circle at a speed of 300 m/s, by what factor would its centripetal acceleration change?

a. | 0.25 |

b. | 0.50 |

c. | 1.00 |

d. | 2.00 |

e. | 4.00 |

ANS:Â DÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- A car enters a level, unbanked semi-circular hairpin turn of 100 m radius at a speed of 28 m/s. The coefficient of friction between the tires and the road is
*m*= 0.800. If the car maintains a constant speed of 28 m/s, it will

a. | attempt to dig into the road surface. |

b. | tend to veer toward the center of the semicircle. |

c. | arrive safely at the end of the semicircle. |

d. | tend to veer toward the outside of the circle. |

e. | veer toward the center for the first quarter-circle, then veer toward the outside for the second quarter-circle. |

- A car enters a level, unbanked semi-circular hairpin turn of 300 m radius at a speed of 40 m/s. The coefficient of friction between the tires and the road is
*m*= 0.25. If the car maintains a constant speed of 40 m/s, it will

a. | attempt to dig into the road surface. |

b. | tend to veer toward the center of the semicircle. |

c. | arrive safely at the end of the semicircle. |

d. | tend to veer toward the outside of the circle. |

e. | veer toward the center for the first quarter-circle, then veer toward the outside for the second quarter-circle. |

- If a 20-kg object dropped in air has a terminal speed of 60 m/s, what was its acceleration at 30 m/s?

a. | 9.80 m/s^{2} |

b. | 7.35 m/s^{2} |

c. | 4.90 m/s^{2} |

d. | 2.45 m/s^{2} |

e. | More information is needed to answer this question. |

- If a dense 20.0-kg object is falling in air at half its terminal velocity, what is the drag force on the object at this moment?

a. | 24.5 N |

b. | 49.0 N |

c. | 69.3 N |

d. | 98.0 N |

e. | 139 N |

- What is the net force on a 10-kg solid steel sphere falling in air at terminal speed?

a. | 980 N |

b. | 200 N |

c. | 98 N |

d. | 49 N |

e. | Some value other than those given above. |

ANS:Â EÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

**PROBLEM**

- A sample of blood is placed into a centrifuge of radius 15.0 cm. The mass of a red corpuscle is 3.0 Â´ 10
^{–}^{16}kg, and the centripetal force required to make it settle out of the plasma is 4.0 Â´ 10^{–}^{11}N. At how many revolutions per second should the centrifuge be operated?

ANS:

150 rev/s (9 000 rpm)

PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- A space station in the form of a large wheel, 120 m in diameter, rotates to provide an “artificial gravity” of 3.00 m/s
^{2}for persons located at the outer rim. Find the rotational frequency of the wheel (in revolutions per minute) that will produce this effect.

ANS:

2.14 rpm

PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- An airplane pilot experiences weightlessness as she passes over the top of a loop-the-loop maneuver. If her speed is 200 m/s at the time, find the radius of the loop.

ANS:

4 080 m

PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A race car starts from rest on a circular track of radius 400 m. Its speed increases at the constant rate of 0.500 m/s
^{2}. At the point where the magnitudes of the radial and tangential accelerations are equal, determine (a) the speed of the race car, and (b) the elapsed time.

ANS:

14.1 m/s, 28.3 s

PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- A small dense object is suspended from the rear view mirror in a car by a lightweight fiber. As the car is accelerating at 1.90 m/s
^{2}, what angle does the string make with the vertical?

ANS:

11.0 degrees

PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

**Chapter 7â€”Energy of a System**

**MULTIPLE CHOICE**

- A constant force of 12 N in the positive
*x*direction acts on a 4.0-kg object as it moves from the origin to the point Â m. How much work is done by the given force during this displacement?

a. | +60 J |

b. | +84 J |

c. | +72 J |

d. | +48 J |

e. | +57 J |

- A 5.0-kg object is pulled along a horizontal surface at a constant speed by a 15-N force acting 20Â° above the horizontal. How much work is done by this force as the object moves 6.0 m?

a. | 78 J |

b. | 82 J |

c. | 85 J |

d. | 74 J |

e. | 43 J |

- A 2.0-kg projectile moves from its initial position to a point that is displaced 20 m horizontally and 15 m above its initial position. How much work is done by the gravitational force on the projectile?

a. | +0.29 kJ |

b. | -0.29 kJ |

c. | +30 J |

d. | -30 J |

e. | -50 J |

- How much work is done by a person lifting a 2.0-kg object from the bottom of a well at a constant speed of 2.0 m/s for 5.0 s?

a. | 0.22 kJ |

b. | 0.20 kJ |

c. | 0.24 kJ |

d. | 0.27 kJ |

e. | 0.31 kJ |

- A 2.5-kg object falls vertically downward in a viscous medium at a constant speed of 2.5 m/s. How much work is done by the force the viscous medium exerts on the object as it falls 80 cm?

a. | +2.0 J |

b. | +20 J |

c. | -2.0 J |

d. | -20 J |

e. | +40 J |

- A 2.0-kg particle has an initial velocity of Â m/s. Some time later, its velocity is Â m/s. How much work was done by the resultant force during this time interval, assuming no energy is lost in the process?

a. | 17 J |

b. | 49 J |

c. | 19 J |

d. | 53 J |

e. | 27 J |

- A block is pushed across a rough horizontal surface from point A to point B by a force (magnitude
*P*= 5.4 N) as shown in the figure. The magnitude of the force of friction acting on the block between A and B is 1.2 N and points A and B are 0.5 m apart. If the kinetic energies of the block at A and B are 4.0 J and 5.6 J, respectively, how much work is done on the block by the force*P*between A and B?

a. | 2.7 J |

b. | 1.0 J |

c. | 2.2 J |

d. | 1.6 J |

e. | 3.2 J |

- A constant force of 15 N in the negative
*y*direction acts on a particle as it moves from the origin to the point Â m. How much work is done by the given force during this displacement?

a. | +45 J |

b. | -45 J |

c. | +30 J |

d. | -30 J |

e. | +75 J |

- An object moving along the
*x*axis is acted upon by a force*F*_{x}that varies with position as shown. How much work is done by this force as the object moves from*x*= 2 m to*x*= 8 m?

a. | -10 J |

b. | +10 J |

c. | +30 J |

d. | -30 J |

e. | +40 J |

- A body moving along the
*x*axis is acted upon by a force*F*_{x}that varies with*x*as shown. How much work is done by this force as the object moves from*x*= 1 m to*x*= 8 m?

a. | -2 J |

b. | -18 J |

c. | -10 J |

d. | -26 J |

e. | +18 J |

- A force acting on an object moving along the
*x*axis is given by*F*_{x}= (14*x*– 3.0*x*^{2}) N where*x*is in m. How much work is done by this force as the object moves from*x*= -1 m to*x*= +2 m?

a. | +12 J |

b. | +28 J |

c. | +40 J |

d. | +42 J |

e. | -28 J |

ANS:Â AÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- The force an ideal spring exerts on an object is given by
*F*_{x}= –*kx*, where*x*measures the displacement of the object from its equilibrium (*x*= 0) position. If*k*= 60 N/m, how much work is done by this force as the object moves from*x*= -0.20 m to*x*= 0?

a. | -1.2 J |

b. | +1.2 J |

c. | +2.4 J |

d. | -2.4 J |

e. | +3.6 J |

- A 4.0-kg block is lowered down a 37Â° incline a distance of 5.0 m from point A to point B. A horizontal force (
*F*= 10 N) is applied to the block between A and B as shown in the figure. The kinetic energy of the block at A is 10 J and at B it is 20 J. How much work is done on the block by the force of friction between A and B?

a. | -58 J |

b. | -53 J |

c. | -68 J |

d. | -63 J |

e. | -47 J |

ANS:Â CÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- If the resultant force acting on a 2.0-kg object is equal to Â N, what is the change in kinetic energy as the object moves from Â m to Â m?

a. | +36 J |

b. | +28 J |

c. | +32 J |

d. | +24 J |

e. | +60 J |

- As a 2.0-kg object moves from Â m to Â m, the constant resultant force acting on it is equal to Â N. If the speed of the object at the initial position is 4.0 m/s, what is its kinetic energy at its final position?

a. | 62 J |

b. | 53 J |

c. | 73 J |

d. | 86 J |

e. | 24 J |

ANS:Â BÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging

- A block slides on a rough horizontal surface from point A to point B. A force (magnitude
*P*= 2.0 N) acts on the block between A and B, as shown. Points A and B are 1.5 m apart. If the kinetic energies of the block at A and B are 5.0 J and 4.0 J, respectively, how much work is done on the block by the force of friction as the block moves from A to B?

a. | -3.3 J |

b. | +1.3 J |

c. | +3.3 J |

d. | -1.3 J |

e. | +4.6 J |

- A 2.0-kg block slides down a frictionless incline from point A to point B. A force (magnitude
*P*= 3.0 N) acts on the block between A and B, as shown. Points A and B are 2.0 m apart. If the kinetic energy of the block at A is 10 J, what is the kinetic energy of the block at B?

a. | 27 J |

b. | 20 J |

c. | 24 J |

d. | 17 J |

e. | 37 J |

- A 3.0-kg block is dragged over a rough horizontal surface by a constant force of 16 N acting at an angle of 37Â° above the horizontal as shown. The speed of the block increases from 4.0 m/s to 6.0 m/s in a displacement of 5.0 m. What work was done by the friction force during this displacement?

a. | -34 J |

b. | -64 J |

c. | -30 J |

d. | -94 J |

e. | +64 J |

- A 10-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 0.80 kN/m). The block is initially at rest at its equilibrium position when a force (magnitude
*P*= 80 N) acting parallel to the surface is applied to the block, as shown. What is the speed of the block when it is 13 cm from its equilibrium position?

a. | 0.85 m/s |

b. | 0.89 m/s |

c. | 0.77 m/s |

d. | 0.64 m/s |

e. | 0.52 m/s |

- A 10-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 1.2 kN/m). The block is initially at rest at its equilibrium position when a force (magnitude
*P*) acting parallel to the surface is applied to the block, as shown. When the block is 8.0 cm from the equilibrium position, it has a speed of 0.80 m/s. How much work is done on the block by the force*P*as the block moves the 8.0 cm?

a. | 8.3 J |

b. | 6.4 J |

c. | 7.0 J |

d. | 7.7 J |

e. | 3.9 J |

- A 20-kg block on a horizontal surface is attached to a light spring (force constant = 8.0 kN/m). The block is pulled 10 cm to the right from its equilibrium position and released from rest. When the block has moved 2.0 cm toward its equilibrium position, its kinetic energy is 13 J. How much work is done by the frictional force on the block as it moves the 2.0 cm?

a. | -2.5 J |

b. | -1.4 J |

c. | -3.0 J |

d. | -1.9 J |

e. | -14 J |

- The horizontal surface on which the block slides is frictionless. The speed of the block before it touches the spring is 6.0 m/s. How fast is the block moving at the instant the spring has been compressed 15 cm?
*k*= 2.0 kN/m

a. | 3.7 m/s |

b. | 4.4 m/s |

c. | 4.9 m/s |

d. | 5.4 m/s |

e. | 14 m/s |

- A 2.0-kg block situated on a frictionless incline is connected to a light spring (
*k*= 100 N/m), as shown. The block is released from rest when the spring is unstretched. The pulley is frictionless and has negligible mass. What is the speed of the block when it has moved 0.20 m down the plane?

a. | 76 cm/s |

b. | 68 cm/s |

c. | 60 cm/s |

d. | 82 cm/s |

e. | 57 cm/s |

- A 2.0-kg block sliding on a frictionless horizontal surface is attached to one end of a horizontal spring (
*k*= 600 N/m) which has its other end fixed. The speed of the block when the spring is extended 20 cm is equal to 3.0 m/s. What is the maximum speed of this block as it oscillates?

a. | 4.6 m/s |

b. | 5.3 m/s |

c. | 5.7 m/s |

d. | 4.9 m/s |

e. | 3.5 m/s |

- A 10-kg block on a rough horizontal surface is attached to a light spring (force constant = 1.4 kN/m). The block is pulled 8.0 cm to the right from its equilibrium position and released from rest. The frictional force between the block and surface has a magnitude of 30 N. What is the kinetic energy of the block as it passes through its equilibrium position?

a. | 4.5 J |

b. | 2.1 J |

c. | 6.9 J |

d. | 6.6 J |

e. | 4.9 J |

- A 2.0-kg body moving along the
*x*axis has a velocity*v*_{x}= 5.0 m/s at*x*= 0. The only force acting on the object is given by*F*_{x}= (-4.0*x*) N, where*x*is in m. For what value of*x*will this object first come (momentarily) to rest?

a. | 4.2 m |

b. | 3.5 m |

c. | 5.3 m |

d. | 6.4 m |

e. | 5.0 m |

- A 1.5-kg object moving along the
*x*axis has a velocity of +4.0 m/s at*x*= 0. If the only force acting on this object is shown in the figure, what is the kinetic energy of the object at*x*= +3.0 m?

a. | 18 J |

b. | 21 J |

c. | 23 J |

d. | 26 J |

e. | 8 J |

- The only force acting on a 1.6-kg body as it moves along the
*x*axis is given in the figure. If the velocity of the body at*x*= 2.0 m is 5.0 m/s, what is its kinetic energy at*x*= 5.0 m?

a. | 52 J |

b. | 44 J |

c. | 36 J |

d. | 60 J |

e. | 25 J |

- The only force acting on a 2.0-kg body moving along the
*x*axis is given by*F*_{x}= (2.0*x*) N, where*x*is in m. If the velocity of the object at*x*= 0 is +3.0 m/s, how fast is it moving at*x*= 2.0 m?

a. | 4.2 m/s |

b. | 3.6 m/s |

c. | 5.0 m/s |

d. | 5.8 m/s |

e. | 2.8 m/s |

- The only force acting on a 2.0-kg body as it moves along the
*x*axis is given by*F*_{x}= (12 – 2.0*x*) N, where*x*is in m. The velocity of the body at*x*= 2.0 m is 5.5Â m/s. What is the maximum kinetic energy attained by the body while moving in the +*x*direction?

a. | 36 J |

b. | 39 J |

c. | 43 J |

d. | 46 J |

e. | 30 J |

- The only force acting on a 1.8-kg body as it moves along the
*x*axis is given by*F*_{x}= -(3.0*x*) N, where*x*is in m. If the velocity of the body at*x*= 0 is*v*_{x}= +8.0 m/s, at what value of*x*will the body have a velocity of +4.0 m/s?

a. | 5.7 m |

b. | 5.4 m |

c. | 4.8 m |

d. | 4.1 m |

e. | 6.6 m |

- Two vectors Â and Â are given by Â and . If these two vectors are drawn starting at the same point, what is the angle between them?

a. | 106Â° |

b. | 102Â° |

c. | 110Â° |

d. | 113Â° |

e. | 97Â° |

- If , , and the angle between Â and Â (when the two are drawn starting from the same point) is 60Â°, what is the scalar product of these two vectors?

a. | -13 |

b. | +13 |

c. | +37 |

d. | -37 |

e. | 73 |

- If vectors Â and Â have magnitudes 12 and 15, respectively, and the angle between the two when they are drawn starting from the same point is 110Â°, what is the scalar product of these two vectors?

a. | -76 |

b. | -62 |

c. | -90 |

d. | -47 |

e. | -170 |

- If the vectors Â and Â have magnitudes of 10 and 11, respectively, and the scalar product of these two vectors is -100, what is the magnitude of the sum of these two vectors?

a. | 6.6 |

b. | 4.6 |

c. | 8.3 |

d. | 9.8 |

e. | 7.6 |

- If the scalar product of two vectors, Â and , is equal to -3.5, if , and the angle between the two vectors when they are drawn starting from the same point is equal to 130Â°, what is the magnitude of ?

a. | 2.1 |

b. | 2.5 |

c. | 2.3 |

d. | 2.7 |

e. | 3.1 |

- If , , and , what is the angle between the two vectors when they are drawn starting from the same point?

a. | 118Â° |

b. | 107Â° |

c. | 112Â° |

d. | 103Â° |

e. | 77Â° |

- Two vectors Â and Â are given by Â and . The scalar product of Â and a third vector Â is -16. The scalar product of Â and Â is +18. The
*z*component of Â is 0. What is the magnitude of ?

a. | 7.8 |

b. | 6.4 |

c. | 3.6 |

d. | 5.0 |

e. | 4.8 |

- If Â = 10, Â = 15, and
*a*= 130Â°, determine the scalar product of the two vectors shown.

a. | +96 |

b. | -96 |

c. | +51 |

d. | -51 |

e. | -35 |

- If Â = 5.0, Â = 8.0, and
*a*= 30Â°, determine the scalar product of the two vectors shown.

a. | -35 |

b. | +35 |

c. | -20 |

d. | +20 |

e. | +40 |

- If Â = 6.0, Â = 5.0, and
*a*= 40Â°, determine the scalar product of the two vectors shown.

a. | +19 |

b. | +23 |

c. | -19 |

d. | -23 |

e. | +30 |

- The same constant force is used to accelerate two carts of the same mass, initially at rest, on horizontal frictionless tracks. The force is applied to cart A for twice as long a time as it is applied to cart B. The work the force does on A is W
_{A}; that on B is W_{B}. Which statement is correct?

a. | W_{A} = W_{B}. |

b. | W_{A} = W_{B}. |

c. | W_{A} = 2 W_{B}. |

d. | W_{A} = 4 W_{B}. |

e. | W_{B} = 2 W_{A}. |

- Carts A and B have equal masses and travel equal distances on straight frictionless tracks while a constant force F is applied to A, and a constant force 2F is applied to B. The relative amounts of work done by the two forces are related by

a. | W_{A} = 4 W_{B}. |

b. | W_{A} = 2 W_{B}. |

c. | W_{A} = W_{B}. |

d. | W_{B} = 2 W_{A}. |

e. | W_{B} = 4 W_{A}. |

- Carts A and B have equal masses and travel equal distances D on side-by-side straight frictionless tracks while a constant force F acts on A and a constant force 2F acts on B. Both carts start from rest. The velocities
_{A}and_{B}of the bodies at the end of distance D are related by

a. | _{B} = _{A} . |

b. | _{B} = _{A}. |

c. | _{B} = 2 _{A}. |

d. | _{B} = 4 _{A}. |

e. | = 2 _{A}_{B}. |

- When a ball rises vertically to a height
*h*and returns to its original point of projection, the work done by the gravitational force is

a. | 0. |

b. | –mgh. |

c. | +mgh. |

d. | -2mgh. |

e. | +2mgh. |

ANS:Â AÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- When a crate of mass
*m*is dragged a distance*d*along a surface with coefficient of kinetic friction*m*_{k}, then dragged back along the same path to its original position, the work done by friction is

a. | 0. |

b. | –m_{k}mgd. |

c. | +m_{k}mgd. |

d. | -2m_{k}mgd. |

e. | +2m_{k}mgd. |

- Two balls, A and B, of mass m and 2m respectively, are carried to height
*h*at constant velocity, but B rises twice as fast as A. The work the gravitational force does on B is

a. | one quarter the work done on A. |

b. | one half the work done on A. |

c. | the same as the work done on A. |

d. | twice the work done on A. |

e. | four times the work done on A. |

- Equal amounts of work are performed on two bodies, A and B, initially at rest, and of masses
*M*and 2*M*respectively. The relation between their speeds immediately after the work has been done on them is

a. | v_{A} = v_{B}. |

b. | v_{A} = 2v_{B}. |

c. | v_{A} = v_{B}. |

d. | v_{B} = v_{A}. |

e. | v_{B} = 2v_{A}. |

ANS:Â AÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- Two cannonballs are dropped from a second floor physics lab at height
*h*above the ground. Ball B has four times the mass of ball A. When the balls pass the bottom of a first floor window at height Â above the ground, the relation between their kinetic energies,*K*and_{A}*K*, is_{B}

a. | K = 4_{A}K._{B} |

b. | K = 2_{A}K._{B} |

c. | K = _{A}K._{B} |

d. | K = 2_{B}K._{A} |

e. | K = 4_{B}K._{A} |

- Two clowns are launched from the same spring-loaded circus cannon with the spring compressed the same distance each time. Clown A has a 40-kg mass; clown B a 60-kg mass. The relation between their kinetic energies at the instant of launch is

a. | . |

b. | . |

c. | K = _{A}K._{B} |

d. | . |

e. | . |

- Two clowns are launched from the same spring-loaded circus cannon with the spring compressed the same distance each time. Clown A has a 40-kg mass; clown B a 60-kg mass. The relation between their speeds at the instant of launch is

a. | . |

b. | . |

c. | v_{A} = v_{B}. |

d. | . |

e. | . |

- In a contest, two tractors pull two identical blocks of stone the same distance over identical surfaces. However, block A is moving twice as fast as block B when it crosses the finish line. Which statement is correct?

a. | Block A has twice as much kinetic energy as block B. |

b. | Block B has lost twice as much kinetic energy to friction as block A. |

c. | Block B has lost twice as much kinetic energy as block A. |

d. | Both blocks have had equal losses of energy to friction. |

e. | No energy is lost to friction because the ground has no displacement. |

- If the scalar (dot) product of two vectors is negative, it means that

a. | there was a calculator error. |

b. | the angle between the vectors is less than 90 degrees. |

c. | the angle between the vectors is 90 degrees. |

d. | the angle between the vectors is greater than 270 degrees. |

e. | the angle between the vectors is between 90 and 180 degrees. |

- Two eggs of equal mass are thrown at a blanket with equal velocity. Egg B hits the blanket but egg A hits the wall instead. Compare the work done on the eggs in reducing their velocities to zero.

a. | More work was done on A than on B. |

b. | More work was done on B than on A. |

c. | The amount of work is the same for both. |

d. | It is meaningless to compare the amount of work because the forces were so different. |

e. | Work was done on B, but no work was done on A because the wall did not move. |

- Planets go around the sun in elliptical orbits. The highly exaggerated diagram below shows a portion of such an orbit and the force on the planet at one position along that orbit. The planet is moving to the right. F
_{||}and Â are the components of the force parallel (tangential) and perpendicular (normal) to the orbit. The work they do is W_{||}and . At the position shown

a. | W_{||} slows the planet down; Â speeds it up. |

b. | W_{||} slows the planet down; Â does no work on it. |

c. | W_{||} speeds the planet up; Â does no work on it. |

d. | W_{||} speeds the planet up; Â slows it down. |

e. | W_{||} does no work on it; Â speeds the planet up. |

- A mass attached to the end of a spring is pulled out and released on a surface with friction. The work Â done on the mass by the force exerted by the spring

a. | never has the same sign as the change in energy owing to friction. |

b. | always has the same sign as the change in energy owing to friction. |

c. | has the same sign as the change in energy owing to friction during one half of each cycle. |

d. | never has the same sign as the change in energy owing to friction if the force of friction is greater than the spring force. |

e. | always has the same sign as the change in energy owing to friction if the force of friction is greater than the spring force. |

- The work Â done by the force exerted by the spring on a mass attached to the end of the spring when the mass has displacement
*d*Â is

a. | always negative. |

b. | always positive. |

c. | negative half the time, positive the other half of the time. |

d. | positive more than it is negative. |

e. | negative more than it is positive. |

- A 30-kg child sitting 5.0 m from the center of a merry-go-round has a constant speed of 5.0 m/s. While she remains seated in the same spot and travels in a circle, the work the seat performs on her in one complete rotation is

a. | 0 J. |

b. | 150 J. |

c. | 1 500 J. |

d. | 4 700 J. |

e. | 46 000 J. |

ANS:Â AÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â PTS:Â Â 1Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Easy

- Sally, who weighs 450 N, stands on a skate board while Roger pushes it forward 13.0 m at constant velocity on a level straight street. He applies a constant 100 N force.

a. | The work Roger does on the skateboard is 0 J. |

b. | The work Roger does on the skateboard is 1 300 J. |

c. | The work Sally does on the skateboard is 1 300 J. |

d. | The work Sally does on the skateboard is 5 850 J. |

e. | The work Roger does on the skateboard is 5 850 J. |

- Negative work can be done

a. | by friction on the tires while a car is accelerating without skidding. |

b. | by a spring at the bottom of an elevator shaft when it stops a falling elevator. |

c. | by a hand catching a ball. |

d. | by all of the above. |

e. | only by (b) and (c) above. |

- Positive work can be done

a. | by friction on the tires when a car is accelerating without skidding. |

b. | by a spring when it launches a clown in the air. |

c. | by a hand throwing a ball. |

d. | by all of the above. |

e. | only by (b) and (c) above. |

- The force of static friction exerted on an automobile’s tires by the ground

a. | provides the accelerating force that makes the car move forward. |

b. | does positive work on the car while it is accelerating. |

c. | does negative work on the car while it is decelerating. |

d. | does everything listed in (a), (b) and (c). |

e. | only does positive or negative work as in (b) or (c). |

- The graph below shows how the force on a 0.500 kg particle varies with position. If the particle has speed Â at
*x*= 0.00 m, what is its speed in m/s when*x*= 8.00 m?

a. | 2.00 |

b. | 10.7 |

c. | 14.8 |

d. | 15.0 |

e. | 21.1 |

- The equation below is the solution to a physics problem:

.

The most likely physical situation it describes is

a. | a 2.30 kg cart rolling up a 30Â° incline. |

b. | a 2.30 kg cart rolling down a 30Â° incline. |

c. | a 2.30 kg cart rolling up a 60Â° incline. |

d. | a 2.30 kg cart rolling down a 60Â° incline. |

e. | a 2.30 kg cart rolling down a 90Â° incline. |

- After a skydiver reaches terminal velocity,

a. | the force of gravity no longer performs work on the skydiver. |

b. | work performed by the force of gravity is converted into gravitational potential energy. |

c. | gravitational potential energy is no longer available to the system of the skydiver plus the Earth. |

d. | gravitational potential energy is converted into thermal energy. |

e. | thermal energy is converted into gravitational potential energy. |

- Each of two vectors, Â and , lies along a coordinate axis in the
*xy*plane. Each vector has its tail at the origin, and the dot product of the two vectors is . Which possibility is correct?

a. | Â and Â both lie along the positive x axis. |

b. | Â lies along the positive x axis. Â lies along the negative x axis. |

c. | Â and Â both lie along the positive y axis. |

d. | Â lies along the negative x axis. Â lies along the negative y axis. |

e. | Â lies along the positive y axis. Â lies along the negative y axis. |

- Each of two vectors, Â and , lies along a coordinate axis in the
*xy*plane. Each vector has its tail at the origin, and the dot product of the two vectors is . Which possibility is correct?

a. | Â and Â both lie along the positive x axis. |

b. | Â lies along the positive x axis. Â lies along the negative x axis. |

c. | Â and Â both lie along the positive y axis. |

d. | Â lies along the negative x axis. Â lies along the negative y axis. |

e. | Â lies along the positive y axis. Â lies along the negative x axis. |

- Two identical springs with spring constant 50 N/m support a 5.0 N weight as in the picture below. What is the change in length of each spring when the weight is hung on the springs?

a. | 2.9 cm |

b. | 5.0 cm |

c. | 5.8 cm |

d. | 7.5 cm |

e. | 10.0 cm |

- A baseball is thrown and lands 120 m away. While the ball is in flight, assuming the effect of air friction is negligible, which of the following is true?

a. | At maximum height the ball has its greatest kinetic energy. |

b. | The horizontal component of the baseballâ€™s kinetic energy is constant. |

c. | The vertical component of the baseballâ€™s kinetic energy is constant. |

d. | The mechanical energy of the baseball is greater when nearer to the ground. |

e. | No answer above is correct. |

- A moving particle is subject to conservative forces only. When its kinetic energy decreases by 10 J, what happens to its mechanical energy?

a. | It increases by 10 J. |

b. | It decreases by 10 J. |

c. | It increases, but not necessarily by 10 J. |

d. | It decreases, but not necessarily by 10 J. |

e. | It remains the same. |

- A conservative force on a particle moving along the
*x*axis is given by . Which of the following is a potential that is associated with this force?

a. | |

b. | |

c. | |

d. | |

e. | No answer given above is correct. |

- A particle is subject to the potential . What is the value of the
*y*component of the force on the particle at the point (*x*,*y*) = (2.0, 3.0)?

a. | 24 |

b. | -24 |

c. | 14 |

d. | -14 |

e. | 28 |

**PROBLEM**

- A baseball outfielder throws a baseball of mass 0.15 kg at a speed of 40 m/s and initial angle of 30Â°. What is the kinetic energy of the baseball at the highest point of the trajectory?

ANS:

90 J

PTS:Â Â 2Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Average

- For the potential , find the stable equilibrium point, if any.

ANS:

PTS:Â Â 3Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â DIF:Â Â Â Challenging