Practice Test 10 - 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 $2.0\,\text{kg}$ block rests on a horizontal table. A student pulls it with a $6\,\text{N}$ horizontal force, and the block remains at rest. The friction force is static, and the only other forces are weight and the normal force. What is the magnitude of the friction force on the block?
2. A box is at rest on a rough horizontal surface. A horizontal force of $2\,\text{N}$ is applied to the right, and the box remains at rest. Static friction acts; other forces are weight and normal. What is the direction of the static friction force on the box?
3. A firework explodes at the top of its flight into two fragments. Define the system as both fragments; the explosion forces are internal, and the only significant external force afterward is gravity downward. Immediately after the explosion, compared to just before, the center-of-mass velocity is:
4. A 1.0 kg cart moves at $-2.0\ \text{m/s}$, and later it moves at $+2.0\ \text{m/s}$ along the same line. How does the cart's momentum change?
5. A 0.40 kg mass moves at constant speed in a horizontal circle of radius 1.2 m. At one instant, its velocity is east. What is the direction of the centripetal acceleration at that instant?
6. Two motors each do work $W$ lifting identical loads, but motor 1 takes time $t$ and motor 2 takes $2t$. Which is true about power?
7. Along a straight road, east is positive and west is negative. A car's average velocity over a trip is $0\text{ m/s}$. Which statement must be true?
8. A book slides $1.8\,\text{m}$ to the right on a table while a constant normal force acts upward. What is the work done by the normal force on the book?
9. A cart is attached to an ideal spring along a straight track. Define equilibrium as $x=0$ where the spring is neither stretched nor compressed, and take $+x$ to be away from the wall. The cart is pushed to $x=-0.06\,\text{m}$ (spring compressed) and released. Immediately after release, what is the direction of the spring force on the cart?
10. A cyclist rides at constant speed around a flat circular path. The only horizontal force on the cyclist-bike system is static friction from the ground. What is the direction of that friction force?
11. A moving cart collides with an identical cart at rest on a nearly frictionless track. Afterward, the two carts move together as one object. Which conclusion about energy and momentum is most accurate?
12. A wooden block floats at rest on water. Which relationship between buoyant force $F_B$ and weight $mg$ is correct?
13. On frictionless ice, a $60\,\text{kg}$ skater initially at rest pushes a $20\,\text{kg}$ sled so the sled moves east at $3.0\,\text{m/s}$. Define the system as skater + sled, and assume external forces on the system are negligible during the push. What is the skater's velocity after the push?
14. A mass attached to a spring oscillates in SHM with constant total energy $E$. When the mass is at a point where kinetic energy equals potential energy, what is the kinetic energy?
15. A sled is pulled at constant speed $v$ by a force of magnitude $F$ directed at angle $\theta$ above the horizontal for time $t$. What is the average power delivered by the pulling force?
16. A 3.0 kg box is pulled up a rough ramp at constant velocity. The ramp is $30^\circ$ above horizontal. A rope pulls parallel to the ramp upward. Kinetic friction is present. Which forces act on the box? Stem: Which free-body diagram correctly shows the forces on the box?
17. A 0.20 kg soccer ball moving east strikes a stationary 1.5 kg goalie glove and briefly compresses before rebounding west. During the contact, the ball pushes on the glove and the glove pushes on the ball. While they are in contact, how do the magnitudes of these two forces compare?​
18. A hoop rolls without slipping down a ramp and speeds up. Which statement about static friction on the hoop is correct?
19. A wheel about a fixed axle has net torque clockwise and angular acceleration clockwise. For the same wheel, the angular velocity is doubled but the net torque is unchanged. What happens to the angular acceleration?
20. A wooden block and a plastic block have equal volumes. The plastic block's mass is smaller. What can be concluded?

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