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A man is marooned at rest on level frictionless ice. In desperation, he hurls his shoe to the right at 15 m/s. If the man weighs 720 N and the shoe weighs 4.0 N, the man moves to the left at approximately:


A) 0 m/s
B) 2.1 * 10-2 m/s
C) 8.3 * 10-2 m/s
D) 15 m/s
E) 1.1 m/s

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A 4.0-N puck is traveling at 3.0 m/s. It strikes an 8.0-N puck, which is stationary. The two pucks stick together. Their common final speed is:


A) 1.0 m/s
B) 1.5 m/s
C) 2.0 m/s
D) 2.3 m/s
E) 3.0 m/s

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For a completely inelastic two-body collision the kinetic energy retained by the objects is the same as:


A) the total kinetic energy before the collision
B) the difference in the kinetic energies of the objects before the collision
C) 1/2Mv2com, where M is the total mass and vcom is the velocity of the center of mass
D) the kinetic energy of the more massive body before the collision
E) the kinetic energy of the less massive body before the collision

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If the total momentum of a system is changing:


A) particles of the system must be exerting forces on each other
B) the system must be under the influence of gravity
C) the center of mass must have constant velocity
D) a net external force must be acting on the system
E) none of the above

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What magnitude impulse will give a 2.0-kg object a momentum change of magnitude +50 kg∙m/s?


A) + 25 N∙s
B) - 25 N∙s
C) + 50 N∙s
D) - 50 N∙s
E) + 100 N∙s

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A 10-kg block of ice is at rest on a frictionless horizontal surface. A 1.0-N force is applied in an easterly direction for 1.0 s. During this time interval, the block:


A) acquires a speed of 1 m/s
B) moves 10 cm
C) acquires a momentum of 1.0 kg . m/s
D) acquires a kinetic energy of 0.1 J
E) none of the above

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A 2-kg cart, traveling on a horizontal air track with a speed of 3 m/s, collides with a stationary 4-kg cart. The carts stick together. The impulse exerted by one cart on the other has a magnitude of:


A) 0 N∙s
B) 4 N∙s
C) 6 N∙s
D) 9 N∙s
E) 12 N∙s

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A block moves at 5 m/s in the positive x direction and hits an identical block, initially at rest. A small amount of gunpowder had been placed on one of the blocks. The explosion does not harm the blocks but it doubles their total kinetic energy. After the explosion the blocks move along the x axis and the incident block has a speed of:


A) 1.8 m/s
B) 3.2 m/s
C) 5.0 m/s
D) 6.8 m/s
E) 7.1 m/s

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A 64-kg woman stands on frictionless level ice with a 0.10-kg stone at her feet. She kicks the stone with her foot so that she acquires a velocity of 0.0017 m/s in the forward direction. The velocity acquired by the stone is:


A) 1.1 m/s forward
B) 1.1 m/s backward
C) 0.0017 m/s forward
D) 0.0017 m/s backward
E) none of these

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The center of mass of Earth's atmosphere is:


A) a little less than halfway between the Earth's surface and the outer boundary of the atmosphere
B) near the surface of the Earth
C) near the outer boundary of the atmosphere
D) near the center of the Earth
E) none of the above

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If a projectile hits a stationary target, and the projectile stops while the target moves at the same speed as the incoming speed of the projectile,


A) the mass of the projectile is much less than the mass of the target.
B) the mass of the projectile is equal to the mass of the target.
C) the mass of the projectile is much greater than the mass of the target.
D) nothing can be said about the masses of the projectile and target without further information.
E) this is an unphysical situation and will not actually happen.

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The center of mass of a system of particles obeys an equation similar to Newton's second law where:


A) is the total internal force and m is the total mass of the system
B) is the total internal force and m is the mass acting on the system
C) is the total external force and m is the total mass of the system
D) is the force of gravity and m is the mass of Earth
E) is the force of gravity and m is the total mass of the system

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A very massive object traveling at 10 m/s strikes a light object, initially at rest, and the light object moves off in the direction of travel of the heavy object. If the collision is elastic, the speed of the lighter object is


A) 5.0 m/s
B) 10 m/s
C) 15 m/s
D) 20 m/s
E) Can't tell from the information given.

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A 2.5-kg stone is released from rest and falls toward Earth. After 4.0 s, the magnitude of its momentum is:


A) 98 kg∙m/s
B) 78 kg∙m/s
C) 39 kg∙m/s
D) 24 kg∙m/s
E) 0 kg∙m/s

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A thick uniform wire is bent into the shape of the letter "U" as shown. Which point indicates the location of the center of mass of this wire? A thick uniform wire is bent into the shape of the letter  U  as shown. Which point indicates the location of the center of mass of this wire?   A)  A B)  B C)  C D)  D E)  E


A) A
B) B
C) C
D) D
E) E

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Blocks A and B are moving toward each other along the x axis. A has a mass of 2.0 kg and a velocity of 50 m/s, while B has a mass of 4.0 kg and a velocity of -25 m/s. They suffer an elastic collision and move off along the x axis. The kinetic energy transferred from A to B during the collision is:


A) 0 J
B) 2500 J
C) 5000 J
D) 7500 J
E) 10000 J

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A 1000-kg space probe is motionless in space. To start moving, its main engine is fired for 5 s during which time it ejects exhaust gases at 5000 m/s. At the end of this process it is moving at 20 m/s. The approximate mass of the ejected gas is: A 1000-kg space probe is motionless in space. To start moving, its main engine is fired for 5 s during which time it ejects exhaust gases at 5000 m/s. At the end of this process it is moving at 20 m/s. The approximate mass of the ejected gas is:   A)  0.8 kg B)  4 kg C)  5 kg D)  20 kg E)  25 kg


A) 0.8 kg
B) 4 kg
C) 5 kg
D) 20 kg
E) 25 kg

Correct Answer

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In a one-dimensional collision,


A) a moving object strikes a stationary object, after which the objects move in arbitrary directions.
B) the objects must be moving along the same line before the collision, but may be moving in arbitrary directions after the collision.
C) one of the objects must remain at rest after the collision.
D) one of the objects must be at rest before the collision.
E) all motion, both before and after the collision, must be along the same line.

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A light rope passes over a light frictionless pulley attached to the ceiling. An object with a large mass is tied to one end and an object with a smaller mass is tied to the other end. Starting from rest, the heavier object moves downward, and the lighter object moves upward with an acceleration of the same magnitude. Which of the following statements is true for the system consisting of the two objects?


A) The center of mass remains at rest.
B) The net external force is zero.
C) The velocity of the center of mass is a constant.
D) The acceleration of the center of mass is g, downward.
E) None of the above statements are true.

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Two bodies, A and B, have equal kinetic energies. The mass of A is nine times that of B. The ratio of the momentum of A to that of B is:


A) 1:9
B) 1:3
C) 1:1
D) 3:1
E) 9:1

Correct Answer

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