AP Physics C: Mechanics Unit 4 Practice Test & Exam | 18 Questions

Questions 1-2 refer to the following information.

1. What is the total linear momentum of the system?

(A)$2.0 \hat{i}$ kg⋅m/s(B)$6.0 \hat{i}$ kg⋅m/s(C)$10.0 \hat{i}$ kg⋅m/s(D)$12.0 \hat{i}$ kg⋅m/s

2. What is the velocity of the center of mass of the system?

(A)$+\frac{1}{3} \hat{i}$ m/s(B)$+\frac{2}{3} \hat{i}$ m/s(C)$+1.0 \hat{i}$ m/s(D)$+2.0 \hat{i}$ m/s

Questions 3-5 refer to the following information and graph.

3. What is the total impulse delivered to the object during the 4.0 s interval?

(A)10 N⋅s(B)20 N⋅s(C)30 N⋅s(D)40 N⋅s

4. What is the speed of the object at $t = 4.0$ s?

(A)5.0 m/s(B)10 m/s(C)20 m/s(D)40 m/s

5. What is the average net force exerted on the object over the 4.0 s interval?

(A)2.5 N(B)5.0 N(C)7.5 N(D)10 N

6. The momentum of a particle is given by the vector function $\vec{p}(t) = (3t^2 - 1)\hat{i} + (4t)\hat{j}$ in units of kg⋅m/s. What is the net force acting on the particle at $t = 2$ s?

(A)$6\hat{i} + 4\hat{j}$ N(B)$11\hat{i} + 8\hat{j}$ N(C)$12\hat{i} + 4\hat{j}$ N(D)$12\hat{i}$ N

7. A student wishes to analyze a collision between a tennis ball and a racket. In order to apply the principle of conservation of linear momentum, which of the following must be true about the system chosen for analysis?

(A)The system must include only the tennis ball.(B)The system must include only the racket.(C)The system must include the tennis ball and the racket, and the net external force on this system must be zero.(D)The system must include the tennis ball, the racket, and the Earth, and the net internal force on this system must be zero.

8. An object of mass $m$ has linear momentum $\vec{p}$ and kinetic energy $K$. If the object's speed is doubled, what are its new linear momentum and kinetic energy?

(A)$\vec{p}$ and $2K$(B)$2\vec{p}$ and $2K$(C)$2\vec{p}$ and $4K$(D)$4\vec{p}$ and $4K$

Questions 9-10 refer to the following information.

9. What is the speed of the two-cart system immediately after the collision?

(A)$\frac{1}{4}v_0$(B)$\frac{1}{2}v_0$(C)$v_0$(D)$2v_0$

10. What is the ratio of the final kinetic energy of the system to the initial kinetic energy of the system?

(A)$\frac{1}{4}$(B)$\frac{1}{2}$(C)$1$(D)$2$

11. Which of the following statements correctly distinguishes between elastic and inelastic collisions for an isolated two-object system?

(A)In an elastic collision, both momentum and kinetic energy are conserved; in an inelastic collision, only momentum is conserved.(B)In an elastic collision, only momentum is conserved; in an inelastic collision, both momentum and kinetic energy are conserved.(C)In an elastic collision, only kinetic energy is conserved; in an inelastic collision, only momentum is conserved.(D)In both types of collisions, only momentum is conserved, but the change in kinetic energy is greater in an elastic collision.

12. A 50 kg astronaut at rest in space throws a 2 kg tool away from their body with a speed of 10 m/s relative to the spaceship they are next to. What is the astronaut's recoil speed relative to the spaceship?

(A)0.2 m/s(B)0.4 m/s(C)2.5 m/s(D)5.0 m/s

Questions 13-14 refer to the following scenario.

13. Which pair of values is a possible outcome for the velocities of the 1.0 kg block ($v1$) and the 4.0 kg block ($v2$) after the collision?

(A)$v1 = -3.0$ m/s, $v2 = +2.0$ m/s(B)$v1 = -1.0$ m/s, $v2 = +1.5$ m/s(C)$v1 = +1.0$ m/s, $v2 = +1.0$ m/s(D)$v1 = +3.0$ m/s, $v2 = +2.0$ m/s

14. During the brief moment of collision, the 1.0 kg block exerts a force $\vec{F}{1 \to 2}$ on the 4.0 kg block. According to Newton's Third Law, the 4.0 kg block exerts a force $\vec{F}{2 \to 1}$ on the 1.0 kg block. How do the impulses delivered by these forces, $\vec{J}{1 \to 2}$ and $\vec{J}{2 \to 1}$, compare?

(A)$\vec{J}{1 \to 2} = 4 \vec{J}{2 \to 1}$(B)$\vec{J}{1 \to 2} = \vec{J}{2 \to 1}$(C)$\vec{J}{1 \to 2} = -\vec{J}{2 \to 1}$(D)$\vec{J}{1 \to 2} = -4 \vec{J}{2 \to 1}$

15. An object of mass $M$ at rest explodes into two pieces. Piece 1 has mass $m1$ and moves with velocity $\vec{v}1$. Piece 2 has mass $m2$ and moves with velocity $\vec{v}2$. Which of the following is true for the momenta and kinetic energies of the pieces immediately after the explosion?

(A)$\vec{p}1 + \vec{p}2 = 0$ and $K1 + K2 > 0$(B)$\vec{p}1 + \vec{p}2 = 0$ and $K1 + K2 = 0$(C)$\vec{p}1 + \vec{p}2 > 0$ and $K1 + K2 > 0$(D)$\vec{p}1 + \vec{p}2 > 0$ and $K1 + K2 = 0$

16. A ball is dropped from rest and bounces off a horizontal floor. The ball is in contact with the floor for a time interval $\Delta t$. The net force on the ball during this interval is $\vec{F}_{net}(t)$. The change in the ball's momentum is $\Delta \vec{p}$. Which integral expression correctly represents this change in momentum?

(A)$\Delta \vec{p} = \int{0}^{\Delta t} ( \vec{F}{floor} - m\vec{g} ) dt$(B)$\Delta \vec{p} = \int{0}^{\Delta t} \vec{F}{floor} dt$(C)$\Delta \vec{p} = \int_{0}^{\Delta t} m\vec{g} dt$(D)$\Delta \vec{p} = \frac{1}{\Delta t} \int{0}^{\Delta t} \vec{F}{net}(t) dt$

17. Two pucks collide on a frictionless air hockey table. Puck A has a mass of 0.25 kg and is moving along the x-axis at 2.0 m/s. It collides with Puck B, which has a mass of 0.50 kg and is initially at rest. After the collision, Puck A moves with a velocity of 1.0 m/s at an angle of 30° above the x-axis. What can be concluded about the y-component of Puck B's velocity after the collision?

(A)It is zero.(B)It is +0.25 m/s.(C)It is -0.25 m/s.(D)It is -0.50 m/s.

18. A bullet is fired into a wooden block resting on a frictionless surface, and the bullet becomes embedded in the block. The block and bullet then slide together. Which of the following quantities are conserved for the bullet-block system from the instant before the bullet hits to the instant after it comes to rest inside the block? Section II: Free-Response

(A)Linear momentum only(B)Kinetic energy only(C)Both linear momentum and kinetic energy(D)Neither linear momentum nor kinetic energy

AP Physics C: Mechanics Unit 4: Linear Momentum Practice Exam

Exam Details

A. Multiple-Choice Questions (18 Questions)

AP Physics C: Mechanics Unit 4: Linear Momentum Practice Exam

Exam Details

A. Multiple-Choice Questions (18 Questions)