Practice Test 5 - AP Physics 1

20 questions. Answer them in any order, then submit to see your score and every explanation.

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1. A projectile is launched and later reaches its highest point. At that instant, which component of its velocity must be zero (ignoring air resistance)?
2. Two small spheres interact gravitationally: sphere A has mass $2m$ and sphere B has mass $m$. Their center-to-center distance increases from $r$ to $2r$. How does the gravitational force magnitude change?
3. A box and a person inside it slide together on frictionless ice. The person walks toward the front wall, pushing on the floor; these contact forces are internal to the person+box system, and external horizontal forces are negligible. While the person walks, which best describes the center-of-mass motion of the system?
4. A cart of mass $2m$ moves east at speed $v$, while a cart of mass $m$ moves west at speed $2v$ on the same straight track. Which cart has greater momentum magnitude?
5. Two students on carts (A heavier than B) start at rest on frictionless level track and push each other apart. The system boundary includes both carts and students; the push forces are internal, and vertical normal and weight forces are external but cancel. After they separate, which statement about the system's center-of-mass motion is correct?
6. Two identical-size spheres are sealed. Sphere $U$ has greater mass than sphere $V$. Which inference about internal structure is supported?
7. A disk rolls without slipping at center-of-mass speed $v$. What is the magnitude of the velocity of the point on the rim at the very top (relative to the ground)?
8. A block on a horizontal spring oscillates without friction. At the equilibrium position, the block's kinetic energy is $K_0$ and its spring potential energy is $0$. Later, when the block is at maximum displacement, it is momentarily at rest. Which statement about the energies at maximum displacement is correct?
9. A constant horizontal force $F$ accelerates a cart from rest. At one instant the cart's speed is $v$. What is the instantaneous power delivered by the force then?
10. A small tugboat pulls a large ship using a taut cable. The cable tension is 1.2×$10^4$ N. Comparing the force of the tugboat on the ship and the force of the ship on the tugboat, which is correct?
11. A disk's angular position changes from $1.0$ to $7.0\,\text{rad}$ in $2.0\,\text{s}$. What is average $\omega$?
12. A wheel has $\omega(t)=8-2t$ (rad/s). At what time does it momentarily stop rotating?
13. A block of mass $m$ is released from rest at the top of a frictionless track at height $h$ above the bottom. At the bottom, it compresses a horizontal spring of constant $k$ by a maximum amount $x$. Air resistance is negligible. Which equation correctly describes the energy transformation at maximum compression?
14. Two carts move along the $x$-axis. Cart A has mass $m$ and moves right at speed $2v$. Cart B has mass $2m$ and moves left at speed $v$. Which statement correctly compares their momenta? Assume right is the positive $x$ direction and ignore any interactions.
15. Two objects in space interact gravitationally: object X has mass $2m$ and object Y has mass $3m$, separated by $r$. They are moved so the separation becomes $\tfrac{r}{2}$ with masses unchanged. How does the gravitational force magnitude change?
16. A cart is attached to an ideal spring along a horizontal track. Equilibrium is $x=0$ when the spring is unstretched; +$x$ points right. When the cart is displaced from $x=+0.02\,\text{m}$ to $x=-0.02\,\text{m}$, how does the spring force change?
17. A sealed, rigid container $P$ is filled with material A. An identical container $Q$ is filled with material B. $P$ has greater mass. What is supported?
18. A constant torque of $0.40\,\text{N}\cdot\text{m}$ acts on a wheel, changing its angular momentum by $0.80\,\text{kg}\cdot\text{m}^2/\text{s}$. How long does it act?
19. A record's angular velocity changes from $+8$ to $+2\,\text{rad/s}$ in $3\,\text{s}$. What is $\alpha$?
20. A solid disk of radius $R$ rolls without slipping on a horizontal floor at constant speed $v$. What is the disk's angular speed?

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