Impulse,Momentum, CM Practice Questions

Transcription

1 Name: Date: 1. A 12.0-kilogram cart is moving at a speed of 0.25 meter per second. After the speed of the cart is tripled, the inertia of the cart will be A. unchanged B. one-third as great C. three times greater D. nine times greater 5. A 7.0-kilogram cart, A, and a 3.0-kilogram cart, B, are initially held together at rest on a horizontal, frictionless surface. When a compressed spring attached to one of the carts is released, the carts are pushed apart. After the spring is released, the speed of cart B is 6.0 meters per second, as represented in the diagram below. 2. A golf club hits a stationary kilogram golf ball with an average force of newtons, accelerating the ball to a speed of 44 meters per second. What is the magnitude of the impulse imparted to the ball by the golf club? A. 2.2 N s B. 880 N s C N s D N s 3. What is the magnitude of the gravitational force of attraction between two kilogram soccer balls when the distance between their centers is meter? A N B N C N D N 4. A kilogram cart traveling to the right on a horizontal, frictionless surface at 2.20 meters per second collides head on with a kilogram cart moving to the left at 1.10 meters per second. What is the magnitude of the total momentum of the two-cart system after the collision? A kg m/s B kg m/s C kg m/s D kg m/s What is the speed of cart A after the spring is released? A. 14 m/s B. 6.0 m/s C. 3.0 m/s D. 2.6 m/s 6. Base your answer to the following question on the information below and on your knowledge of physics. A cannonball with a mass of 1.0 kilogram is fired horizontally from a 500.-kilogram cannon, initially at rest, on a horizontal, frictionless surface. The cannonball is acted on by an average force of newtons for second. What is the magnitude of the change in momentum of the cannonball during firing? A. 0 kg m/s B kg m/s C kg m/s D kg m/s 7. A blue lab cart is traveling west on a track when it collides with and sticks to a red lab cart traveling east. The magnitude of the momentum of the blue cart before the collision is 2.0 kilogram meters per second, and the magnitude of the momentum of the red cart before the collision is 3.0 kilogram meters per second. The magnitude of the total momentum of the two carts after the collision is A. 1.0 kg m/s B. 2.0 kg m/s C. 3.0 kg m/s D. 5.0 kg m/s page 1

2 8. A kilogram car traveling 20.0 meters per second east experiences an impulse of newton seconds west. What is the final velocity of the car after the impulse has been applied? 13. An air bag is used to safely decrease the momentum of a driver in a car accident. The air bag reduces the magnitude of the force acting on the driver by A m/s east B m/s east C m/s west D m/s west 9. A 160.-kilogram space vehicle is traveling along a straight line at a constant speed of 800. meters per second. The magnitude of the net force on the space vehicle is A. increasing the length of time the force acts on the driver B. decreasing the distance over which the force acts on the driver C. increasing the rate of acceleration of the driver D. decreasing the mass of the driver A. 0 N B N C N D N 10. A 1.5-kilogram cart initially moves at 2.0 meters per second. It is brought to rest by a constant net force in 0.30 second. What is the magnitude of the net force? A N B N C. 10. N D. 15 N 11. A kilogram ball traveling at 60.0 meters per second hits a concrete wall. What speed must a kilogram bullet have in order to hit the wall with the same magnitude of momentum as the ball? 14. A 15-kilogram cart is at rest on a horizontal surface. A 5-kilogram box is placed in the cart. Compared to the mass and inertia of the cart, the cart-box system has A. more mass and more inertia B. more mass and the same inertia C. the same mass and more inertia D. less mass and more inertia 15. A 7.28-kilogram bowling ball traveling 8.50 meters per second east collides head-on with a 5.45 kilogram bowling ball traveling 10.0 meters per second west. Determine the magnitude of the total momentum of the two-ball system after the collision. A m/s B m/s C m/s D m/s 12. A 3.0-kilogram object is acted upon by an impulse having a magnitude of 15 newton seconds. What is the magnitude of the object s change in momentum due to this impulse? 16. The diagram below shows an 8.0-kilogram cart moving to the right at 4.0 meters per second about to make a head-on collision with a 4.0-kilogram cart moving to the left at 6.0 meters per second. A. 5.0 kg m/s B. 15 kg m/s C. 3.0 kg m/s D. 45 kg m/s After the collision, the 4.0-kilogram cart moves to the right at 3.0 meters per second. What is the velocity of the 8.0-kilogram cart after the collision? A m/s left B m/s right C. 5.5 m/s left D. 5.5 m/s right page 2

3 17. A 5.00-kilogram block slides along a horizontal, frictionless surface at 10.0 meters per second for 4.00 seconds. The magnitude of the block s momentum is A kg m/s B kg m/s C kg m/s D kg m/s 18. When a 1.0-kilogram cart moving with a speed of 0.50 meter per second on a horizontal surface collides with a second 1.0-kilogram cart initially at rest, the carts lock together. What is the speed of the combined carts after the collision? [Neglect friction.] A. 1.0 m/s B m/s C m/s D. 0 m/s 19. A 75-kilogram hockey player is skating across the ice at a speed of 6.0 meters per second. What is the magnitude of the average force required to stop the player in 0.65 second? A. 120 N B. 290 N C. 690 N D. 920 N 20. A 3.1-kilogram gun initially at rest is free to move. When a kilogram bullet leaves the gun with a speed of 500. meters per second, what is the speed of the gun? A. 0.0 m/s B. 2.4 m/s C. 7.5 m/s D m/s 22. A motorcycle being driven on a dirt path hits a rock. Its 60.-kilogram cyclist is projected over the handlebars at 20. meters per second into a haystack. If the cyclist is brought to rest in 0.50 second, the magnitude of the average force exerted on the cyclist by the haystack is A N B N C N D N 23. A 70-kilogram hockey player skating east on an ice rink is hit by a 0.1-kilogram hockey puck moving toward the west. The puck exerts a 50-newton force toward the west on the player. Determine the magnitude of the force that the player exerts on the puck during this collision. [1] 24. Centripetal force F c acts on a car going around a curve. If the speed of the car were twice as great, the magnitude of the centripetal force necessary to keep the car moving in the same path would be A. F c B. 2F c C. F c 2 D. 4F c 25. The instant before a batter hits a 0.14-kilogram baseball, the velocity of the ball is 45 meters per second west. The instant after the batter hits the ball, the ball s velocity is 35 meters per second east. The bat and ball are in contact for second. Calculate the magnitude of the average force the bat exerts on the ball while they are in contact. [Show all work, including the equation and substitution with units.] 21. When Earth and the Moon are separated by a distance of meters, the magnitude of the gravitational force of attraction between them is newtons. What would be the magnitude of this gravitational force of attraction if Earth and the Moon were separated by a distance of meters? A N B N C N D N 26. Base your answer(s) to the following question(s) on the information below. A 1200-kilogram car moving at 12 meters per second collides with a 2300-kilogram car that is waiting at rest at a traffic light. After the collision, the cars lock together and slide. Eventually, the combined cars are brought to rest by a force of kinetic friction as the rubber tires slide across the dry, level, asphalt road surface. Calculate the speed of the locked-together cars immediately after the collision. [Show all work, including the equation and substitution with units.] page 3

4 27. Calculate the magnitude of the frictional force that brings the locked-together cars to rest. [Show all work, including the equation and substitution with units.] 31. The diagram below represents two masses before and after they collide. Before the collision, mass m A is moving to the right with speed v, and mass m B is at rest. Upon collision, the two masses stick together. 28. A 0.45-kilogram football traveling at a speed of 22 meters per second is caught by an 84-kilogram stationary receiver. If the football comes to rest in the receiver s arms, the magnitude of the impulse imparted to the receiver by the ball is A N s B. 9.9 N s C. 4.4 N s D. 3.8 N s 29. A carpenter hits a nail with a hammer. Compared to the magnitude of the force the hammer exerts on the nail, the magnitude of the force the nail exerts on the hammer during contact is A. less B. greater C. the same 30. As a meteor moves from a distance of 16 Earth radii to a distance of 2 Earth radii from the center of Earth, the magnitude of the gravitational force between the meteor and Earth becomes A. 1 8 as great B. 8 times as great C. 64 times as great D. 4 times as great Which expression represents the speed, v 1, of the masses after the collision? [Assume no outside forces are acting on m A or m B ] A. C. m A + m B v m A B. m B v m A + m B D. m A + m B m A v m A v m A + m B 32. A 1.0-kilogram laboratory cart moving with a velocity of 0.50 meter per second due east collides with and sticks to a similar cart initially at rest. After the collision, the two carts move off together with a velocity of 0.25 meter per second due east. The total momentum of this frictionless system is A. zero before the collision B. zero after the collision C. the same before and after the collision D. greater before the collision than after the collision 33. A bicycle and its rider have a combined mass of 80. kilograms and a speed of 6.0 meters per second. What is the magnitude of the average force needed to bring the bicycle and its rider to a stop in 4.0 seconds? A N B N C N D N page 4

5 34. Which situation will produce the greatest change of momentum for a 1.0-kilogram cart? 37. Which two quantities can be expressed using the same units? A. accelerating it from rest to 3.0 m/s B. accelerating it from 2.0 m/s to 4.0 m/s C. applying a net force of 5.0 N for 2.0 s D. applying a net force of 10.0 N for 0.5 s A. energy and force B. impulse and force C. momentum and energy D. impulse and momentum 35. In the diagram below, scaled vectors represent the momentum of each of two masses, A and B, sliding toward each other on a frictionless, horizontal surface. 38. In the diagram below, a block of mass M initially at rest on a frictionless horizontal surface is struck by a bullet of mass m moving with horizontal velocity v. Which scaled vector best represents the momentum of the system after the masses collide? A. B. C. D. What is the velocity of the bullet-block system after the bullet embeds itself in the block? A. C. ( M + v M ) m B. ( m + v ) m D. M ( m + M m ) v ( m ) v m + M 36. A 3.0-kilogram steel block is at rest on a friction-less horizontal surface. A 1.0-kilogram lump of clay is propelled horizontally at 6.0 meters per second toward the block as shown in the diagram below. 39. The diagram here shows a 1-kilogram aluminum sphere and a 3-kilogram copper sphere of equal radius located 20 meters above the ground. Upon collision, the clay and steel block stick together and move to the right with a speed of Just before striking the ground, the speed of the copper sphere is 20 meters per second. What is the momentum of the copper sphere? A. 1.5 m/s B. 2.0 m/s C. 3.0 m/s D. 6.0 m/s A. 10 kg-m/sec B. 20 kg-m/sec C. 60 kg-m/sec D. 600 kg-m/sec page 5

6 40. When objects exert forces on each other, the total momentum of the system A. decreases B. increases C. remains the same 45. The diagram shown represents two objects at rest on a frictionless horizontal surface with a spring compressed between them. When the compressed spring is released, the two objects are pushed apart. 41. The momentum of a 5-kilogram object moving at 6 meters per second is A. 1 kg m/sec B. 5 kg m/sec C. 11 kg m/sec D. 30 kg m/sec 42. In the diagram shown, a 10-kilogram ball is fired with a velocity of 500 meters per second from a 1,000-kilogram cannon. What is the recoil velocity of the cannon? What is the total momentum of the two-object system that is shown after the expansion of the spring? A. 20 kg-m/s B. 10 kg-m/s C. 5.0 kg-m/s D. 0 kg-m/s 46. What is the velocity of the 2.0-kilogram object that is shown after being acted on by 10 newton-seconds of impulse? A. 1.0 m/s B. 2.0 m/s C. 5.0 m/s D. 10 m/s A. 5 m/sec B. 2 m/sec C. 10 m/sec D. 500 m/sec 43. As a 1.0-kilogram mass falls freely to the Earth, its momentum A. decreases B. increases C. remains the same 44. A reaction engine acquires motion by ejecting hot gases in the opposite direction. This is an example of the law of A. conservation of heat B. conservation of energy C. conservation of momentum D. conservation of mass 47. If the 1.0-kilogram object that is shown receives an impulse of 20 newton-seconds, what impulses does the 2.0-kilogram object receive? A. 0 N-s B N-s C. +10 N-s D. +20 N-s 48. As the unbalanced force applied to an object increases, the time rate of change of the object s momentum A. decreases B. increases C. remains the same 49. A rocket with a mass of 1,000 kilograms is moving at a speed of 20 meters per second. The magnitude of the momentum is A. 50 kg m/s B. 200 kg m/s C. 20,000 kg m/s D. 400,000 kg m/s page 6

7 50. An unbalanced 6.0-newton force acts eastward on an object for 3.0 seconds. The impulse produced by the force is A. 18 N s east B. 2.0 N s east C. 18 N s west D. 2.0 N s west 51. What is the magnitude of the velocity of a 25-kilogram mass that is moving with a momentum of 100 kilogram-meters per second? A m/s B m/s C. 40 m/s D. 4.0 m/s 52. A 2.0-kilogram rifle initially at rest fires a kilogram bullet. As the bullet leaves the rifle with a velocity of 500 meters per second, what is the momentum of the rifle-bullet system? A. 2.5 kg m/s B. 2.0 kg m/s C. 0.5 kg m/s D. 0 kg m/s 53. Which pair of terms are vector quantities? 54. A constant braking force of 10 newtons applied for 5 seconds is used to stop a 2.5-kilogram cart traveling at 20 meters per second. The magnitude of the impulse applied to stop the cart is A. 10 N s B. 30 N s C. 50 N s D. 100 N s 55. A kilogram bullet is fired from a rifle by an unbalanced force of 200 newtons. If the force acts on the bullet for 0.1 second, what is the maximum speed attained by the bullet? A. 5 m/s B. 20 m/s C. 400 m/s D. 800 m/s 56. A 2.0-kilogram ball traveling north at 4.0 meters per second collides head on with a 1.0-kilogram ball traveling south at 8.0 meters per second. What is the magnitude of the total momentum of the two balls after collision? A. 0 kg m/s B. 8.0 kg m/s C. 16 kg m/s D. 32 kg m/s A. force and mass B. distance and displacement C. momentum and acceleration D. speed and velocity 57. Two rocks weighing 5 newtons and 10 newtons, respectively, fall freely from rest near the Earth s surface. After 3 seconds of free-fall, compared to the 5-newton rock, the 10-newton rock has greater A. acceleration B. height C. momentum D. speed page 7

8 58. Two railroad carts, A and B, are on a frictionless, level track. Cart A has a mass of kilograms and a velocity of 3.0 meters per second toward the right. Cart B has a velocity of 1.5 meters per second toward the left. The magnitude of the momentum of cart B is kilogram-meters per second. When the two carts collide, they lock together. a) What is the magnitude of the momentum of cart A before the collision? (Show all calculations, including equation and substitutions with units.) b) On the diagram, construct a scaled vector that represents the momentum of cart A before the collision. The momentum vector must be drawn to a scale of 1.0 centimeter = 1,000 kilogram-meters per second. [Be sure your final answer has the correct labels (numbers and units).] c) In one or more complete sentences, describe the momentum of the two carts after the collision and justify your answer based on the initial momenta of both carts. 59. A 2.0-kilogram toy cannon is at rest on a frictionless surface. A remote triggering device causes a kilogram projectile to be fired from the cannon. Which equation describes this system after the cannon is fired? A. mass of cannon + mass of projectile = 0 B. speed of cannon + speed of projectile = 0 C. momentum of cannon + momentum of projectile = 0 D. velocity of cannon + velocity of projectile = If a net force of 10 newtons acts on a 6.0-kilogram mass for 8.0 seconds, the total change of momentum of the mass is A. 48 kg m/s B. 60 kg m/s C. 80 kg m/s D. 480 kg m/s 62. As shown in the diagrams, a lump of clay travels horizontally to the right toward a block at rest on a frictionless surface. Upon collision, the clay and the block stick together and move to the right. Compared to the total momentum of the clay and the block before the collision, the momentum of the clay-block system after the collision is 61. Compared to the inertia of a 0.10-kilogram steel ball, the inertia of a 0.20-kilogram Styrofoam ball is A. one-half as great B. twice as great A. less B. greater C. the same C. the same D. four times as great page 8

9 63. The accompanying velocity-time graph represents the motion of a 3-kilogram cart along a straight line. The cart starts at t = 0 and initially moves north. 65. A kilogram car collides with a tree and is brought to rest in 0.50 seconds by an average force of newtons. What is the magnitude of the impulse on the car during this 0.50 second interval? A kg s B N s C N/s D N kg s 66. In the diagram below, a 60.-kilogram rollerskater exerts a 10.-newton force on a 30.-kilogram rollerskater for 0.20 second. What is the magnitude of the change in momentum of the cart between t = 0 and t = 3 seconds? A. 20 kg m/s B. 30 kg m/s C. 60 kg m/s D. 80 kg m/s 64. What is the momentum of a kilogram car as it travels at 30 meters per second due east for 60 seconds? A kg m/s, east B kg m/s, west What is the magnitude of the impulse applied to the 30.-kilogram rollerskater? A. 50. N s B. 2.0 N s C. 6.0 N s D. 12 N s C kg m, east D kg m, west page 9