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Multiple Choice problems-exam2-solutions

# Multiple Choice problems-exam2-solutions - 1 Which one of...

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Unformatted text preview: 1. Which one of the following statements concerning kinetic energy is true? A. It can be measured in watts. B. It is always equal to the potential energy. C. It is always positive. D. It is a quantitative measure of inertia. E. It is directly proportional to velocity. 2. In which one of the following situations will there be an increase in kinetic energy? A. A projectile approaches its maximum height. B. A box is pulled across a rough floor at constant speed. C. A child pushes a merry go round causing it to rotate faster. D. A satellite travels in a circular orbit around the earth at fixed altitude. E. A stone at the end of a string is whirled in a horizontal circle at constant speed. 3. An elevator supported by a single cable descends a shaft at a constant speed. The only forces acting on the elevator are the tension in the cable and the gravitational force. Which one of the following statements is true? A. The magnitude of the work done by the tension force is larger than that done by the gravitational force. B. The magnitude of the work done by the gravitational force is larger than that done by the tension force. C. The work done by the tension force is zero joules. D. The work done by the gravitational force is zero joules. E. The net work done by the two forces is zero joules. 4. Two balls of equal size are dropped from the same height from the roof of a building. One ball has twice the mass of the other. When the balls reach the ground, how do the kinetic energies of the two balls compare? A. The lighter one has one fourth as much kinetic energy as the other does. B. The lighter one has one half as much kinetic energy as the other does. C. The lighter one has the same kinetic energy as the other does. D. The lighter one has twice as much kinetic energy as the other does. E. The lighter one has four times as much kinetic energy as the other does. 5. A block is dropped from a high tower and is falling freely under the influence of gravity. Which one of the following statements is true concerning this situation? Neglect air resistance. A. As the block falls, the net work done by all of the forces acting on the block is zero joules. B. The kinetic energy increases by equal amounts over equal distances. C. The kinetic energy of the block increases by equal amounts in equal times. D. The potential energy of the block decreases by equal amounts in equal times. E. The total energy of the block increases by equal amounts over equal distances. 6. A rock is thrown straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the rock as it rises? Neglect air resistance. A. The total energy of the rock increases. B. The kinetic energy increases and the potential energy decreases. C. Both the potential energy and the total energy of the rock increase. D. The kinetic energy decreases and the potential energy increases. E. Both the kinetic energy and the potential energy of the rock remain the same. 7. Complete the following statement: A force that acts on an object is said to be conservative if A. it obeys Newton's laws of motion. B. it results in a change in the object's kinetic energy. C. it always acts in the direction of motion of the object. D. the work it does on the object is independent of the path of the motion. E. the work it does on the object is equal to the increase in the object's kinetic energy. 8. Which one of thefollowing choices is an example of a conservative force? A. tension B. static frictional force C. elastic spring force D. normal force E. motor propulsion force 9. Which one of the following choices is an example of a non‐conservative force? A. gravitational force B. kinetic frictional force C. electrical force D. elastic spring force 10. The force component acting on an object along the displacement varies with the displacement s as shown in the graph. Determine the work done on the object as it travels from s = 0.0 to 12 m. A. 48 J B. 57 J C. 66 J D. 81 J 11. A rock is dropped from a high tower and falls freely under the influence of gravity. Which one of the following statements is true concerning the rock as it falls? A. It will gain an equal amount of momentum during each second. B. It will gain an equal amount of kinetic energy during each second. C. It will gain an equal amount of speed for each meter through which it falls. D. It will gain an equal amount of momentum for each meter through which it falls. E. The amount of momentum it gains will be proportional to the amount of potential energy that it loses. 12. A stunt person jumps from the roof of a tall building, but no injury occurs because the person lands on a large, air‐filled bag. Which one of the following best describes why no injury occurs? A. The bag provides the necessary force to stop the person. B. The bag reduces the impulse to the person. C. The bag increases the amount of time the force acts on the person and reduces the change in momentum. D. The bag decreases the amount of time during which the momentum is changing and reduces the average force on the person. E. The bag increases the amount of time during which the momentum is changing and reduces the average force on the person. 13. In which one of the following situations is linear momentum not conserved? A. A bomb suspended by a string explodes into one hundred fragments. B. A bowling ball collides with ten pins. C. A golf ball is struck by a club. D. An astronaut floating in space throws a hammer away and subsequently moves in the opposite direction. E. A tree limb is struck by lightning and falls to the ground. 14. A stationary bomb explodes in space breaking into a number of small fragments. At the location of the explosion, the net force due to gravity is zero newtons. Which one of the following statements concerning this event is true? A. Kinetic energy is conserved in this process. B. The fragments must have equal kinetic energies. C. The sum of the kinetic energies of the fragments must be zero. D. The vector sum of the linear momenta of the fragments must be zero. E. The velocity of any one fragment must be equal to the velocity of any other fragment. 15. An object of mass 3m, initially at rest, explodes breaking into two fragments of mass m and 2m, respectively. Which one of the following statements concerning the fragments after the explosion is true? A. They may fly off at right angles. B. They may fly off in the same direction. C. The smaller fragment will have twice the speed of the larger fragment. D. The larger fragment will have twice the speed of the smaller fragment. E. The smaller fragment will have four times the speed of the larger fragment. 16. A sled of mass m is coasting on the icy surface of a frozen river. While it is passing under a bridge, a package of equal mass m is dropped straight down and lands on the sled (without causing any damage). The sled plus the added load then continue along the original line of motion. How does the kinetic energy of the sled + load compare with the original kinetic energy of the sled? A. It is 1/4 the original kinetic energy of the sled. B. It is 1/2 the original kinetic energy of the sled. C. It is 3/4 the original kinetic energy of the sled. D. It is the same as the original kinetic energy of the sled. E. It is twice the original kinetic energy of the sled. 17. Which one of the following is characteristic of an inelastic collision? A. Total mass is not conserved. B. Kinetic energy is not conserved. C. Total energy is not conserved. D. The change in momentum is less than the total impulse. E. Linear momentum is not conserved. 18. Complete the following statement: Momentum will be conserved in a two‐body collision only if A. both bodies come to rest. B. the collision is perfectly elastic. C. the kinetic energy of the system is conserved. D. the net external force acting on the two‐body system is zero. E. the internal forces of the two body system cancel in action‐reaction pairs. 19. A tennis ball has a velocity of 12 m/s downward just before it strikes the ground and bounces up with a velocity of 12 m/s upward. Which statement is true concerning this situation? A. The momentum of the ball and the momentum of the earth both change. B. Neither the momentum of the ball nor the momentum of the earth changes. C. The momentum of the ball is changed; the momentum of the earth is not changed. D. The momentum of the ball is unchanged; the momentum of the earth is changed. E. Both the momentum and the kinetic energy of the ball change because of the collision. 20. Two objects constitute an isolated system. In a perfectly elastic collision between the two objects, which one of the following statements is a false statement? A. The total kinetic energy is conserved. B. The kinetic energy of each object is the same before and after the collision. C. The total momentum is conserved. D. The magnitude of the force exerted by each object on the other object is equal. E. The total kinetic energy before the collision is equal to the total kinetic energy after the collision. 21. Which one of the following statements concerning center of mass is true? A. All of an object’s mass is located at its center of mass. B. The center of mass of an object must be located within the object. C. The center of mass of a system of objects cannot change even if there are forces acting on the objects. D. The velocity of the center of mass of a system of objects is greatly affected by a collision of objects within the system. E. The velocity of the center of mass of a system of objects is constant when the sum of the external forces acting on the system is zero. 22. A lump of clay is thrown at a wall. A rubber ball of identical mass is thrown with the same speed toward the same wall. Which statement is true? A. The clay experiences a greater change in momentum than the ball. B. The ball experiences a greater change in momentum than the clay. C. The clay and the ball experience the same change in momentum. D. It is not possible to know which object has the greater change in momentum. 23. Object 1 has twice the mass of Object 2. Both objects have the same kinetic energy. Which of the following statements is true? A. Both objects can have the same magnitude of momentum. B. Object 1 has a momentum of greater magnitude than Object 2. C. The magnitude of the momentum of Object 2 is four times that of Object 1. D. All the statements are false. 24. An astronaut tosses a ball out in space where gravitational fields may be neglected. What will happen to the ball? A. It will stop as soon as the force the astronaut gave it is used up. B. It will stop when the energy the astronaut gave it runs out. C. It will stop after a short time because there is no gravity to keep it moving. D. It will move in a circle like a boomerang. E. It will be slowed down very gradually by collisions with molecules in space. ...
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