AP Physics 1 Unit 4 Multiple Choice

Select all correct answers: Skater 1 has a smaller mass than Skater 2. Initially, they start together at rest and then push each other. Which of the following statements must be true?

• Skater 1 experiences a greater change in momentum

• Skater 2 experiences a greater change in momentum

• Skater 1 has a greater velocity than Skater 2 after the push

• Skater 1 experienced a greater force during the push

• Both skaters experienced the same amount of force during the push

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

Object X of mass 4 kg travels with a speed of 3 m/s toward object Y of mass 2 kg that is initially at rest. Object X then collides completely inelastically with object Y. How much mechanical energy is converted into nonmechanical energy during the collision?

• 0 J

• 6 J

• 9 J

• 10 J

• 12 J

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NGSS.HS-PS2-2

A stationary object explodes, breaking into three pieces of masses m, m, and 3m. The two pieces of mass m move off at right angles to each other with the same magnitude of momentum mV. What are the magnitude of the velocity of the piece having mass 3m?

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NGSS.HS-PS2-2

Two people of unequal mass are initially standing still on ice with negligible friction. They then simultaneously push each other horizontally. Afterward, which of the following is true?

• The kinetic energies of the two people are equal.

• The speeds of the two people are equal.

• The momenta of the two people are of equal magnitude.

• The center of mass of the two-person system moves in the direction of the less massive person.

• The less massive person has a smaller initial acceleration than the more massive person.

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

Two particles collide and stick together. If no external forces act on the two particles, which of the following is correct for the change in total momentum Δp and the change in total kinetic energy ΔK of the two particles?

• Δp < 0 and ΔK <0

• Δp < 0 and ΔK = 0

• Δp = 0 and ΔK < 0

• Δp = 0 and ΔK = 0

• Δp = 0 and ΔK > 0

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NGSS.HS-PS2-2

A dog of mass 10 kg sits on a skateboard of mass 2 kg that is initially traveling south at 2 m/s. The dog jumps off with a velocity of 1 m/s north relative to the ground. Which of the following is the best estimate of the velocity of the skateboard immediately after the dog has jumped?

• 1 m/s north

• 1 m/s south

• 3 m/s south

• 7 m/s south

• 17 m/s south

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NGSS.HS-PS2-1

NGSS.HS-PS2-2

In an experiment, a variable net force is applied to an object. A graph of the net force exerted on the object as a function of time is shown. Which of the following experiments could have been conducted to represent the variable net force shown in the graph?

• A 0.2 kg object increases its speed from 2 m/s to 8 m/s.

• A 1 kg object increases its speed from 2 m/s to 4 m/s.

• A 2 kg object increases its speed from 1 m/s to 3 m/s.

• A 3 kg object increases its speed from 0 m/s to 1 m/s.

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NGSS.HS-PS2-1

Two identical blocks are connected to the opposite ends of a compressed spring. The blocks initially slide together on a frictionless surface with velocity v to the right. The spring is then released by remote control. At some later instant, the left block is moving at v/2 to the left, and the other block is moving to the right. What is the speed of the center of mass of the system at that instant?

• 2v

• 3v/2

• v

• v/2

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NGSS.HS-PS2-2

Two lumps of clay with masses m and 2m are traveling in opposite directions with speed 3v, as shown above. The lumps of clay collide and stick together. What is the speed of the combined lump of clay after the collision?

• Zero

• v

• 2v

• 3v

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NGSS.HS-PS2-2

Two identical spaceships are traveling in deep space, far from any planets or stars. The ships travel in the same direction, with the slower one directly behind the faster one. The ships are connected by a cable attached to a spool, so that the part of the cable outside the ships can be made longer or shorter as needed. The cable is used to bring the ships to the same speed for a transfer of cargo. The graph above shows the speed of the two ships during a 10 s interval. Which of the following graphs best represents the net force exerted on the two-ship system?

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NGSS.HS-PS2-1

NGSS.HS-PS2-2