Practice Test 9 - 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 mass on a spring oscillates in SHM without damping. At the turning point, the spring potential energy is $9\,\text{J}$. What is the total mechanical energy of the system?
2. A $2.0\,\text{kg}$ block initially at rest is pushed right by $10\,\text{N}$ for $0.30\,\text{s}$. What is $\Delta \vec p$?
3. Two samples have equal mass. Sample $X$ occupies less volume than sample $Y$. Which inference about density is valid?
4. A satellite moves in a circular orbit around Earth at constant speed. Ignoring air resistance and thrust, what is the direction of the satellite's net force?
5. Two blocks connected by a light spring rest on a frictionless horizontal surface. The system boundary includes both blocks and the spring; spring forces are internal, and external horizontal forces are negligible. The spring is compressed and released. What happens to the center-of-mass motion of the system?
6. A student swings a rubber stopper in a horizontal circle at constant speed. The string breaks when the stopper is at the south point of the circle. Immediately after the break, which direction does the stopper initially travel?
7. A glider attached to a spring oscillates in SHM on a frictionless air track. The equilibrium position is at the center. At the turning points, the glider stops briefly: kinetic energy is $0$ and spring potential energy is maximum. At equilibrium, the glider's speed is maximum and spring potential energy is minimum. Total mechanical energy stays constant. Consider two instants: instant 1 at $x=A/3$ and instant 2 at $x=2A/3$ (both measured from equilibrium). Which statement compares the kinetic energies at instants 1 and 2?
8. A constant horizontal force $F$ accelerates a cart from rest on a frictionless track. At time $t$, the cart's speed is $v$. At time $2t$, its speed is $2v$. How does instantaneous power compare at $t$ and $2t$?
9. A ball is moving downward through water at constant speed. Forces are weight $mg$ downward, buoyant force upward, and drag upward. Which statement is correct?
10. A student stands on a frictionless turntable holding two 2.0 kg dumbbells at arm's length, rotating at angular speed $ omega_0$. External torque about the vertical axis is negligible. The student pulls the dumbbells close to the body, decreasing the system's rotational inertia to one-fourth its initial value. Which statement best describes the final angular speed?
11. A block attached to a spring oscillates in SHM without friction. When the block passes through equilibrium, displacement is zero and speed is greatest, so kinetic energy is greatest and spring potential energy is smallest; total mechanical energy stays constant. Which statement about potential energy at equilibrium is correct?
12. A block attached to an ideal spring is on a frictionless surface. Define equilibrium position as $x=0$ at the spring's natural length and take $+x$ right. The block is at $x=+0.03\,\text{m}$ at one instant and at $x=-0.03\,\text{m}$ at another. How do the spring-force magnitudes compare?
13. A box slides right on a horizontal surface and slows down. Kinetic friction is present; air resistance is negligible. Which horizontal force acts on the box?
14. Two carts collide in one dimension on a nearly frictionless track; high-speed video shows they bounce apart and return to their original speeds (opposite directions). Which claim is correct?​
15. A metal sphere is released from rest in oil and begins sinking with increasing speed. Which statement about forces is correct?
16. Two objects, $m$ and $2m$, are separated by distance $r$ in deep space. Compared with the force on $m$, what is the force on $2m$?
17. A ball of mass $m$ moves west at speed $v$, and a second ball of mass $m$ moves east at speed $v$. Which statement about their momenta is correct?
18. A ball of mass $m$ is thrown straight upward from the ground with speed $v$. At a later time, its speed is $\tfrac{v}{3}$ while still moving upward. Ignoring air resistance, how does its kinetic energy at that later time compare to its initial kinetic energy?
19. A $0.20\,\text{kg}$ ball is suspended from the ceiling by a light string and hangs at rest. Air resistance is negligible. Which forces act on the ball?
20. A mass–spring oscillator moves with negligible friction. At maximum displacement from equilibrium, the speed is zero so kinetic energy is zero and spring potential energy is maximum; total mechanical energy is constant. Which statement about kinetic energy at the turning point is correct?

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