Base your answers to questions 1 and 2 on the information and diagram below. The diagram shows the top view of a -kilogram student at point A on an amusement park ride. The ride spins the student in a horizontal circle of radius meters, at a constant speed of meters per second. The floor is lowered and the student remains against the wall without falling to the floor. 4. A car going around a curve is acted upon by a centripetal force, F. If the speed of the car were twice as great, the centripetal force necessary to keep it moving in the same path would be A) F B) 2F C) F/2 D) 4F 5. Student A lifts a 50.-newton box from the floor to a height of 0.40 meter in 2.0 seconds. Student B lifts a 40.-newton box from the floor to a height of 0.50 meter in 1.0 second. Compared to student A, student B does A) the same work but develops more power B) more work but develops less power C) less work but develops more power D) the same work but develops less power 1. The magnitude of the centripetal force acting on the student at point A is approximately A) B) C) D) 6. Base your answer to the following question on A ball attached to a string is moved at constant speed in a horizontal circular path. A target is located near the path of the ball as shown in the diagram. 2. Which vector best represents the direction of the centripetal acceleration of the student at point A. A) B) C) D) 3. Which statement best explains why a wet saw used to cut through fine optical crystals is constantly lubricated with oil? A) Lubrication decreases friction and minimizes the B) Lubrication decreases friction and maximizes the C) Lubrication increases friction and minimizes the D) Lubrication increases friction and maximizes the At which point along the ball s path should the string be released, if the ball is to hit the target? A) A B) B C) C D) D Page 1
7. A car uses its brakes to stop on a level road. During this process, there must be a conversion of kinetic energy into 10. The diagram below shows an ideal simple pendulum. A) internal energy B) light energy C) nuclear energy D) gravitational potential energy 8. Base your answer to the following question on the diagram below which represents a flat racetrack as viewed from above, with the radii of its two curves indicated. A car with a mass of 1,000 kilograms moves counterclockwise around the track at a constant speed of 20 meters per second. As the pendulum swings from position A to position B, what happens to its total mechanical energy? [Neglect friction] A) It remains the same. B) It decreases. C) It increases. 11. Base your answer to the following question on the information below. The net force acting on the car while it is moving from D to C is A) 4,000 N B) 0 N C) 200 N D) 20,000 N A boy pushes his wagon at constant speed along a level sidewalk. The graph below represents the relationship between the horizontal force exerted by the boy and the distance the wagon moves. 9. A 70.-kilogram cyclist develops 210 watts of power while pedaling at a constant velocity of 7.0 meters per second east. What average force is exerted eastward on the bicycle to maintain this constant speed? A) 490 N B) 30. N C) 3.0 N D) 0 N What is the total work done by the boy in pushing the wagon 4.0 meters? A) 180 J B) 7.5 J C) 120 J D) 5.0 J Page 2
12. As shown in the diagram below, a child applies a constant 20.-newton force along the handle of a wagon which makes a 25 angle with the horizontal. 15. Base your answer to the following question on A block weighing 40. newtons is released from rest on an incline 8.0 meters above the horizontal, as shown in the diagram below. How much work does the child do in moving the wagon a horizontal distance of 4.0 meters? A) 73 J B) 34 J C) 80. J D) 5.0 J If 50. joules of internal energy is generated as the block slides down the incline, the maximum kinetic energy of the block at the bottom of the incline is A) 270 J B) 320 J C) 3100 J D) 50. J 13. An unbalanced force of 40. newtons keeps a 5.0-kilogram object traveling in a circle of radius 2.0 meters. What is the speed of the object? A) 8.0 m/s B) 2.0 m/s C) 16 m/s D) 4.0 m/s 16. Base your answer to the following question on on the information below. In an experiment, a 0.028-kilogram rubber stopper is attached to one end of a string. A student whirls the stopper overhead in a horizontal circle with a radius of 1.0 meter. The stopper completes 10. revolutions in 10. seconds. 14. Base your answer to the following question on A block weighing 15 Newtons is pulled to the top of an incline that is 0.20 meter above the ground, as shown below. If 4.0 joules of work are needed to pull the block the full length of the incline, what is the total change in internal energy of the block and incline? A) 7.0 J B) 1.0 J C) 3.0 J D) 0.0 J Determine the speed of the whirling stopper. Page 3
17. Base your answer to the following question on the information and diagram below. A roller coaster cart starts from rest and accelerates, due to gravity, down a track. The cart starts at a height that enables it to complete a loop in the track. [Neglect friction.] 19. As a box is pushed 30. meters across a horizontal floor by a constant horizontal force of 25 newtons, the kinetic energy of the box increases by 300. joules. How much total internal energy is produced during this process? A) 150 J B) 250 J C) 450 J D) 750 J 20. The diagram below represents a 0.40-kilogram stone attached to a string. The stone is moving at a constant speed of 4.0 meters per second in a horizontal circle having a radius of 0.80 meter. The magnitude of the centripetal force keeping the cart in circular motion would be greatest at point A) A B) B C) C D) D 18. The work done in accelerating an object along a frictionless horizontal surface is equal to the object's change in A) velocity B) momentum C) kinetic energy D) potential energy The magnitude of the centripetal acceleration of the stone is A) 0.0 m/s 2 B) 2.0 m/s 2 C) 5.0 m/s 2 D) 20. m/s 2 Page 4
Answer Key UCM & Energy Review 1. A 2. C 3. A 4. D 5. A 6. B 7. A 8. A 9. B 10. A 11. C 12. A 13. D 14. B 15. A 16. 6.3 m/s 17. A 18. C 19. C 20. D Page 5