Physics Samples: Q3 Exam Part A 1. If a 3.0-kilogram object moves 10. meters in 2.0 seconds, its average momentum is (A) 60. kg-m/sec (C) 15 kg-m/sec (B) 30. kg-m/sec (D) 10. kg-m/sec 2. A net force of 12 Newtons acting north on an object for 4.0 seconds will produce an impulse of (A) 48 kg-m/sec north (C) 3.0 kg-m/sec north (B) 48 kg-m/sec south (D) 3.0 kg-m/sec south 3. A mass with a momentum of 40. kg•m/s receives an impulse of 30. N•s in the direction of its motion. The final momentum of the mass is (A) 1.3 kg•m/s (C) 70. kg•m/s (B) 10. kg•m/s (D) 1,200 kg•m/s 4. A 2-newton force acts on a mass. If the momentum of the mass changes by 120 kg-meters/sec., the force acts for a time of (A) 8 sec. (C) 60 sec. (B) 30 sec. (D) 120 sec. 5. What is the magnitude of the change in momentum produced when a force of 5.0 Newtons acts on a l0-kilogram object for 3.0 seconds? (A) 1.5 kg-m/sec (C) 10 kg-m/sec (B) 5.0 kg-m/sec (D) 15 kg-m/sec 6. A 0.050-kilogram bullet is fired from a 4.0 kilogram rifle that is initially at rest. If the bullet leaves the rifle with momentum having a magnitude of 20. kilogram•meters per second, the rifle will recoil with a momentum having a magnitude of (A) 1,600 kg•m/s (C) 20. kg•m/s (B) 80. kg•m/s (D) 0.25 kg•m/s Base your answers to questions 7 and 8 on the diagram below which represents carts A and B being pushed apart by a spring which exerts an average force of 50. Newtons for a period of 0.20 second. [Assume friction-less conditions.] 7. Compared to the magnitude of the impulse acting on cart A, the magnitude of the impulse acting on cart B is (A) one-half as great (C) the same (B) twice as great (D) four times as great 8. Compared to the total momentum of the carts before the spring is released, the total momentum of the carts after the spring is released is (A) one-half as great (C) the same (B) twice as great (D) four times as great Q3ExamSampsD1 Name ____________________ 9. A constant force of 2.0 Newtons is used to push a 3.0-kilogram mass 4.0 meters across the floor. How much work is done on the mass? (A) 6.0 J (C) 12 J (B) 8.0 J (D) 24 J 10. How much work is done on a downhill skier by an average braking force of 9.8 × 102 Newtons to stop her in a distance of 10. meters? (A) 1.0 × 101 J (B) 9.8 × 101 J (C) 1.0 × 103 J (D) 9.8 × 103 J 11. A horizontal force of 40 Newtons pushes a block along a level table at a constant speed of 2 meters per second. How much work is done on the block in 6 seconds? (A) 80 J (C) 240 J (B) 120 J (D) 480 J 12. A net force of 5.0 Newtons moves a 2.0-kilogram object a distance of 3.0 meters in 3.0 seconds. How much work is done on the object? (A) 1.0 J (C) 15 J (B) 10. J (D) 30. J 13. When a machine does 250 joules of work in 10. seconds, the power developed by the machine will be (A) 2,500 watts (C) 240 watts (B) 260 watts (D) 25 watts 14. How long would it take a machine to do 5,000 joules of work if the power rating of the machine is 100 watts? (A) 5,000 sec (C) 10 sec (B) 50 sec (D) 0.2 sec 15. A crane raises a 200-newton weight to a height of 50 meters in 5 seconds. The crane does work at the rate of (A) 8 × 10–1 W (B) 2 × 101 W (C) 2 × 103 W (D) 5 × 104 W 16. A force of 10 Newtons is required to move an object at a constant speed of 5 meters per second. The power used is (A) 0.5 W (C) 5 W (B) 2 W (D) 50 W 17. As a bullet shot vertically upward rises, the kinetic energy of the bullet (A) decreases (C) remains the same (B) increases 18. Base your answer to the following question on the diagram below that shows an object at A that moves over a frictionless surface from A to E. The object has a mass of M. The object's kinetic energy at point C is less than its kinetic energy at point (A) A (C) D (B) B (D) E 23. In the accompanying diagram, a 1.0-kilogram sphere at point A has a potential energy of 5.0 joules. What is the potential energy of the sphere at point B, halfway down the incline? (A) 0.0 J (C) 3.0 J (B) 2.5 J (D) 5.0 J 19. If the kinetic energy of an object is 16 joules when its speed is 4.0 meters per second, then the mass of the objects is (A) 0.5 kg (C) 8.0 kg (B) 2.0 kg (D) 19.6 kg 24. If a 5-kilogram mass is raised vertically 2 meters from the surface of the Earth, its gain in potential energy is approximately (A) 0 J (C) 20 J (B) 10 J (D) 100 J 20. If the velocity of a moving object is doubled, the object's kinetic energy is (A) unchanged (C) doubled (B) halved (D) quadrupled 25. A spring has a spring constant of 120 newtons per meter. How much potential energy is stored in the spring as it is stretched 0.20 meter? (A) 2.4 J (C) 12 J (B) 4.8 J (D) 24 J 21. An object with a speed of 20. meters per second has a kinetic energy of 400. joules. The mass of the object is (A) 1.0 kg (C) 0.50 kg (B) 2.0 kg (D) 40. kg 22. Base your answer to the following question on the information and diagram below. An inclined plane is 10 meters long and is elevated 5 meters on one end as shown. Starting from rest at the top of the incline, a box weighing 100 Newtons accelerates down the incline at a rate of 2.5 meters per second2. 26. At a height of 10 meters above the earth's surface, the potential energy of a 2-kilogram mass is 196 joules. After the mass which starts at rest falls 5 meters, its kinetic energy will be (A) 196 J (C) 98 J (B) 147 J (D) 49 J 27. If a 2.0-kilogram mass is raised 0.05 meter vertically, the work done on the mass is approximately (A) 0.10 J (C) 40. J (B) 0.98 J (D) 100 J 28. Sixteen joules of work was required to lift a 2.0-kilogram object from the floor to a table. How much potential energy was gained by the 2.0-kilogram object? (A) 0.80 joule (C) 16 joules (B) 8.0 joules (D) 32 joules The potential energy of the box at the top of the incline was approximately (A) 1,000 J (C) 50 J (B) 500 J (D) 0 J Q3ExamSampsD1 29. A 40-newton object is released from rest at a height of 10 meters above the earth's surface. Just before it hits the ground, its kinetic energy will be closest to (A) 0 joules (C) 800 joules (B) 400 joules (D) 1,200 joules Answer Key Q3_ExamSamplesD1 1. C 2. A 3. C 4. C 5. D 6. C 7. C 8. C 9. B 10. D 11. D 12. C 13. D 14. B 15. C 16. D 17. A 18. B 19. B 20. D 21. B 22. B 23. B 24. D 25. A 26. C 27. B 28. C 29. B Q3ExamSampsD1