1.

During which of the labeled segments on the graph is the object moving but not accelerating?

2. The object has a speed of 2 m/s at which of the following times?

3. An object falls freely from rest under the influence of gravity. If air resistance is negligible，the ratio of the distances traveled during each1一second time interval by the object during the first, second，and third seconds of its fall is

4.

Four directions at point Z are indicated as I，II，III and IV in the figure above. Which of the arrows best indicates the direction of the acceleration of the sphere at point Z?

5. Four directions at point Y are indicated as I，II，III and IV in the figure above. Directions I and III are vertical，II and IV are horizontal, and I is directed along the string．Which of  the following best indicates the direction of the acceleration of the sphere at point Y?

6. 6A block of mass m is pulled by a rope along a horizontal surface with negligible friction. For time>0，the magnitude of the acceleration of the object as a function of time is given by the equation a=Ae^-kt, where A and k are positive constants. Which of the following expressions determines the impulse exerted on the block by the rope during the time interval 0<t<t₁？

7.

A 300 g cart with a force sensor attached starts at rest on a track. The force sensor exerts a force on the cart to speed it up. The graph above shows the force F exerted by the sensor on the cart as a function of time t. The change in the cart’s momentum during the time interval shown is most nearly

8.

In terms of K_x, the gravitational potential energy of the planet-satellite X system is

9. The kinetic energy of satellite X is K_x. The satellite Y is K_Y. The ratio K_x/K_Y is

10. Satellite X is moved to the same orbit as satellite Y by a force doing work on the satellite. In terms of Kx the work done on satellite X by the force is

11. Car A can travel around a curved section of road without skidding at a maximum constant speed of 10ms· When car B travels around the same curve without skidding at its maximum speed，it has twice the centripetal acceleration as car A. The maximum speed at which car B can safely travel around the curve is most nearly

12. A car is traveling down the highway at speed v when the driver slams on the brakes and skids to a stop in a distance d. Assuming the same frictional force, how far would the car slide if its speed was 2v?

13. 13·A 3.0 kg block accelerates at 2.0m/s because of  a constant net force. A block of unknown mass accelerates at 6.0m/s because of the same net force. What is the mass of the second block?

14. 14A cart is moving to the right with a constant speed of 20m/s· A box of mass 80kg moves with the cart without slipping. The coefficient of static friction between the box and cart is 0.30，and the coefficient of kinetic friction between the box and cart is 0.15. What are the magnitude and direction of the frictional force acting on the box as it moves with the cart?