Risky Questions
AP Physics 1 Units 1-3
Rules
1. A cart is constrained to move along a straight line. A varying net force along the direction of motion is exerted on the cart. The cart’s velocity v as a function of time t is shown in the graph below. The five labeled points divide the graph into four sections. For which segment does the cart move the greatest distance?��A) AB C) CD �B) BC D) DE
2. A horizontal, uniform board of weight 125 N and length 4 m is supported by vertical chains at each end. A person weighing 500 N is sitting on the board. The tension in the right chain is 250 N. What is the tension in the left chain?�A) 250 N B) 375 N C) 500 N D) 625 N
3. A cart is constrained to move along a straight line. A varying net force along the direction of motion is exerted on the cart. The cart’s velocity v as a function of time t is shown in the graph above. The five labeled points divide the graph into four sections. During some part of the motion, the work done on the cart is negative. What feature of the motion indicates this?�A) The speed is decreasing.�B) The speed is increasing.�C) The acceleration is positive.�D) The acceleration is negative.
4. A compressed spring mounted on a disk can project a small ball. When the disk is not rotating, as shown in the top view to the right, the ball moves radially outward. The disk then rotates in a counterclockwise direction as seen from above, and the ball is projected outward at the instant the disk is in the position shown above. Which of the following best shows the subsequent path of the ball relative to the ground?��A) B) C)���D) E)
5. An object attached to one end of a string moves in a circle at constant speed. Which of the following is correct?��A) The object is accelerating as it moves.�B) The object’s velocity is the same as its speed.�C) The object does not require a force to keep its state of circular motion.�D) If the string breaks, the object will keep its circular motion.�E) If the string breaks, the object will move radially away from the center of the circle.
6. While traveling in its elliptical orbit around the Sun, Mars gains speed during the part of the orbit where it is getting closer to the Sun. Which of the following can be used to explain this gain in speed?�A) As Mars gets closer to the Sun, the Mars–Sun system loses potential energy and Mars gains kinetic energy.�B) A component of the gravitational force exerted on Mars is perpendicular to the direction of motion, causing an acceleration and hence a gain in speed along that direction.�C) The torque exerted on Mars by the Sun during this segment of the orbit increases the Mars–Sun system’s angular momentum.�D) The centripetal force exerted on Mars is greater than the gravitational force during this segment of the orbit, causing Mars to gain speed as it gets closer to the Sun.
8. An object of mass m=3.0kg is attached to one end of a string with negligible mass and length L=0.80m. The object is released from rest at time t=0, when the string is horizontal. At time t=t1 the object is at the location shown in the figure, where the string is vertical. Which of the following is most nearly the magnitude of the tension in the string at time t=t1? �A) 4 N B) 30 N C) 60 N D) 90 N
9. An object of mass m is initially at rest and free to move without friction in any direction in the xy-plane. A constant net force of magnitude F directed in the +x direction acts on the object for 1 s. Immediately thereafter a constant net force of the same magnitude F directed in the +y direction acts on the object for 1 s. After this, no forces act on the object.�Question�Which of the following graphs best represents the kinetic energy K of the object as a function of time?�A) C) �����B) D)
10. A person driving a car suddenly applies the brakes. The car takes 4 s to come to rest while traveling 20 m at constant acceleration. Can the speed of the car immediately before the brakes were applied be determined without first determining the car’s acceleration?��A) Yes, by dividing the distance (20 m) by the time (4 s).�B) Yes, by determining the average speed while braking and doubling it.�C) No, because the acceleration is needed to use standard equations such as Δx = vot + 1/2 at2.�D) No, because the fundamental relationship that defines velocity contains acceleration.
11. A constant force F0 is exerted continuously on a block that is initially at rest on a horizontal surface. The change in kinetic energy of the block while the block is moved from position x=0 to x=50cm is ΔK1, and the change in kinetic energy of the block as the block is moved from x=50cm to x=100cm is ΔK2. How does ΔK1 compare to ΔK2, and why?��A) ΔK2=ΔK1 because the velocity increases by the same amount between 0cm to 50cm and between 50cm to 100cm.�B) ΔK2=ΔK1 because the applied force does the same work on the block between 0cm to 50cm and between 50cm to 100cm.�C) ΔK2>ΔK1 because the block is moving faster on average between 50cm to 100cm than it is between 0cm to 50cm.�D) ΔK2>ΔK1 because the rate of change of kinetic energy is greater between 50cm to 100cm than it is between 0cm to 50cm.
12. An object is moving in the positive x-direction while a net force directed along the x-axis is exerted on the object. The figure above shows the force as a function of position. What is the net work done on the object over the distance shown?��A) F0d B) 3F0d/2 C) 2F0d D) 4F0d
13. An object is thrown with an initial speed v near the surface of Earth. Assume that air resistance is negligible and the gravitational field is constant. If the object is thrown vertically upward, the direction and magnitude of its acceleration while it is in the air is� A) upward and decreasing� B) upward and constant� C) downward and decreasing� D) downward and increasing� E) downward and constant
14. Block A hangs from a light string that passes over a light pulley and is attached to block B, which is on a level horizontal frictionless table, as shown below. Students are to determine the mass of block B from the motion of the two-block system after it is released from rest. They plan to measure the time block A takes to reach the floor. The students must also take which of the following measurements to determine the mass of block B?�A) Only the mass of block A�B) Only the distance block A falls to reach the floor�C) Only the mass of block A and the distance block A falls to reach the floor�D) The mass of block A, the distance block A falls to reach the floor, and the radius of the pulley
15. A person exerts an upward force on a box, as shown above. The box may be moving upward, downward, or not at all while the person exerts the upward force. For which of the following motions of the box is the work done by the person on the box correctly indicated?��A) ��B) ��C) ��D) �
16. A 2 kg block, starting from rest, slides 20 m down a frictionless inclined plane from X to Y, dropping a vertical distance of 10 m as shown above. The speed of the block at point Y is most nearly��A) 7 m/s B) 10 m/s C) 14 m/s �D) 20 m/s E) 100 m/s
17. The figure to the right shows the forces exerted on a block that is sliding on a horizontal surface: the gravitational force of 40 N, the 40 N normal force exerted by the surface, and a frictional force exerted to the left. The coefficient of friction between the block and the surface is 0.20. The acceleration of the block is most nearly:�A) 1.0 m/s2 to the right�B) 1.0 m/s2 to the left�C) 2.0 m/s2 to the right�D) 2.0 m/s2 to the left
18. A constant force of 900 N pushes a 100 kg mass up the inclined plane shown above at a uniform speed of 4 m/s. The power developed by the 900 N force is most nearly:��A) 400 W�B) 800 W�C) 900 W�D) 1000 W�E) 3600 W
19. A block is released from rest and slides down a ramp. The surface of the ramp has three rough sections where the friction between the surface and the block is not negligible, as shown by the shaded regions below. Measuring which of the following will allow for the best estimate of the block’s instantaneous acceleration when the block is at the midpoint of the ramp?�A) The total distance traveled by the block and the total elapsed time�B) The final speed of the block and the total elapsed time�C) The distance between points just before and just after the midpoint and the time it takes the block to travel between them�D) The speed of the block at points just before and just after the midpoint and the time it takes the block to travel between them
20. Two satellites are in circular orbits around Earth. Satellite 1 has mass m0 and an orbital radius of 2RE, where RE is the radius of Earth. Satellite 2 has mass 2m0 and an orbital radius of 3RE. Which of the following correctly compares the magnitude F of the force exerted by Earth on each satellite and the speed v of each satellite?��A) C) ����B) D)