Work-Energy Review PDF

1. A 15.0-kilogram mass is moving at 7.50 meters per 7. If the kinetic energy of a given mass is to be doubled, second on a horizontal, frictionless surface. What is its speed must be multiplied by the total work that must be done on the mass to...

1. A 15.0-kilogram mass is moving at 7.50 meters per 7. If the kinetic energy of a given mass is to be doubled, second on a horizontal, frictionless surface. What is its speed must be multiplied by the total work that must be done on the mass to A) 8 B) 2 C) D) 4 increase its speed to 11.5 meters per second? 8. If the kinetic energy of a 10-kilogram object is 2,000 A) 120. J B) 422 J joules, its velocity is C) 570. J D) 992 J A) 10 meters/sec. B) 20 meters/sec. 2. A 75-kilogram bicyclist coasts down a hill at a C) 100 meters/sec. D) 400 meters/sec. constant speed of 12 meters per second. What is the kinetic energy of the bicyclist? 9. When a teacher shines light on a photocell attached to a fan, the blades of the fan turn. The brighter the light A) 4.5 10 2 J B) 9.0 10 2 J shone on the photocell, the faster the blades turn. C) 5.4 10 3 J D) 1.1 l0 4 J Which energy conversion is illustrated by this 3. The table below lists the mass and speed of each of demonstration? four objects. A) light ® thermal ® mechanical B) light ® nuclear ® thermal C) light ® electrical ® mechanical D) light ® mechanical ® chemical 10. If the direction of a moving car changes and its speed remains constant, which quantity must remain the same? A) velocity B) momentum C) displacement D) kinetic energy Which two objects have the same kinetic energy? A) A and D B) B and D C) A and C D) B and C 4. An object moving at a constant speed of 25 meters per second possesses 450 joules of kinetic energy. What is the object’s mass? A) 0.72 kg B) 1.4 kg C) 18 kg D) 36 kg 5. 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 B) 2.0 kg C) 0.50 kg D) 40. kg 6. When the speed of an object is halved, its kinetic energy is A) quartered B) halved C) the same D) doubled 11. 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. Compared to the kinetic energy of the car while moving from A to D, the kinetic energy of the car while moving from D to C is A) less B) greater C) the same 12. 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 B) B C) D D) E 13. The gravitational potential energy, with respect to Earth, that is possessed by an object is dependent on the object’s A) acceleration B) momentum C) position D) speed 14. Which situation describes a system with decreasing gravitational potential energy? A) a girl stretching a horizontal spring B) a bicyclist riding up a steep hill C) a rocket rising vertically from Earth D) a boy jumping down from a tree limb 15. Which graph best represents the relationship between the gravitational potential energy of an object near the surface of Earth and its height above Earth's surface? A) B) C) D) 16. A spring gains 2.34 joules of elastic potential energy as it is compressed 0.250 meter from its equilibrium position. What is the spring constant of this spring? A) 9.36 N/m B) 18.7 N/m C) 37.4 N/m D) 74.9 N/m Base your answers to questions 17 through 20 on the information below. In a laboratory investigation, a student applied various downward forces to a vertical spring. The applied forces and the corresponding elongations of the spring from its equilibrium position are recorded in the data table below. Directions: Construct a graph on the grid below, following the directions below. 17. Using your graph, calculate the spring constant of this spring. [Show all work, including the equation and substitution with units.] 18. Draw the best-fit line or curve. 19. Plot the data points for force versus elongation. 20. Mark an appropriate scale on the axis labeled "Force (N)." 21. When a spring is compressed 2.50 x 10 –2 meter from 22. The diagram below shows a toy cart possessing 16 its equilibrium position, the total potential joules of kinetic energy traveling on a frictionless, energy stored in the spring is 1.25 x 10 –2 joule. horizontal surface toward a horizontal spring. Calculate the spring constant of the spring. [Show all work, including the equation and substitution with units.] If the cart comes to rest after compressing the spring a distance of 1.0 meter, what is the spring constant of the spring? A) 32 N/m B) 16 N/m C) 8.0 N/m D) 4.0 N/m 23. How much work is done by the force lifting a 28. A force of 80. Newtons pushes a 50.-kilogram object 0.1-kilogram hamburger vertically upward at across a level floor for 8.0 meters. The work done is constant velocity 0.3 meter from a table? A) 10 J B) 400 J A) 0.03 J B) 0.1 J C) 640 J D) 3,920 J C) 0.3 J D) 0.4 J 29. The work done in accelerating an object along a 24. As shown in the diagram below, a child applies a frictionless horizontal surface is equal to the change constant 20.-newton force along the handle of a in the object’s wagon which makes a 25° angle with the horizontal. A) momentum B) velocity C) potential energy D) kinetic energy 30. The diagram below shows a moving, 5.00-kilogram cart at the foot of a hill 10.0 meters high. For the cart to reach the top of the hill, what is the minimum kinetic energy of the cart in the position shown? [Neglect energy loss due to friction.] How much work does the child do in moving the wagon a horizontal distance of 4.0 meters? A) 5.0 J B) 34 J C) 73 J D) 80. J A) 4.91 J B) 50.0 J 25. How much work is done on a downhill skier by an C) 250. J D) 491 J average braking force of 9.8 × 102 Newtons to stop 31. The diagram below shows three positions, A, B, and her in a distance of 10. meters? C, in the swing of a pendulum, released from rest at A) 1.0 × 10 1 J B) 9.8 × 10 1 J point A. [Neglect friction.] C) 1.0 × 10 3 J D) 9.8 × 10 3 J 26. Which combination of units can be used to express work? A) newton second meter B) newton meter Which statement is true about this swinging second pendulum? C) newton/meter A) The potential energy at A equals the kinetic D) newton meter energy at C. 27. Which action would require no work to be done on B) The speed of the pendulum at A equals the an object? speed of the pendulum at B. C) The potential energy at B equals the potential A) lifting the object from the floor to the ceiling energy at C. B) pushing the object along a horizontal floor D) The potential energy at A equals the kinetic against a frictional force energy at B. C) decreasing the speed of the object until it comes to rest D) holding the object stationary above the ground 32. A pendulum is made from a 7.50-kilogram mass 33. A 55.0-kilogram diver falls freely from a diving attached to a rope connected to the ceiling of a platform that is 3.00 meters above the surface of the gymnasium. The mass is pushed to the side until it is water in a pool. When she is 1.00 meter above the at position A, 1.5 meters higher than its equilibrium water, what are her gravitational potential energy position. After it is released from rest at position A, and kinetic energy with respect to the water’s the pendulum moves freely back and forth between surface? positions A and B, as shown in the diagram below. A) PE = 1620 J and KE = 0 J B) PE = 1080 J and KE = 540 J C) PE = 810 J and KE = 810 J D) PE = 540 J and KE = 1080 J 34. As an object falls freely, the kinetic energy of the object A) decreases B) increases C) remains the same 35. The wrecking crane shown below is moving toward a brick wall which is to be torn down. What is the total amount of kinetic energy that the mass has as it swings freely through its equilibrium position? [Neglect friction.] At what point in the swing of the wrecking ball A) 11 J B) 94 J C) 110 J D) 920 J should the ball make contact with the wall to make a collision with the greatest kinetic energy? A) 1 B) 2 C) 3 D) 4