1. A hoop and a solid disk both have the same radius and mass and negligible thickness. Assume that they are both rotating with the same constant angular speed. Which has the higher rotational kinetic energy?
the hoop
the disk
They both have the same rotational kinetic energy.
impossible to determine

2. Which of the following screwdrivers would likely be the most effective to loosen a stubborn screw? Assume the size of the driver head is the same in each case.
one with a handle that is 8 cm long and 2 cm wide
one with a handle that is 12 cm long and 2 cm wide
one with a handle that is 8 cm long and 4 cm wide
They would all loosen the screw just as effectively.

3. With which wrench would you have the best success in loosening a bolt
With which wrench would you have the best success in loosening a bolt? Assume that the socket part of the wrench is the same size in each case.
one in which the handle is 10 cm long and 2 cm wide
one in which the handle is 12 cm long and 2 cm wide
one in which the handle is 10 cm long and 4cm wide
They would all loosen the bolt just as effectively.

4. Your electric drill has been on for a period of time and you turn it off. The time interval for the rotating bit to come to rest due to frictional torque is Δt. You replace the bit with a smaller one that results in a smaller moment of inertia of the entire rotating mechanism of the drill by a factor of 2/3. When this smaller bit is rotated at the same angular speed as the first and the drill is turned off, the frictional torque remains the same as that for the previous situation. Choose the time for this second bit to come to rest. .

5. A rod attached to the shaft of a motor at the center of the rod so that the rod is perpendicular to the shaft, as in figure a. The motor is turned on and performs work W on the rod, accelerating it to an angular speed ω. The system is brought to rest and the attachment to the rod is then moved along the shaft such that the rod is spun from its end instead, as in figure b. If the controls of the motor are adjusted such that the rod is accelerated from rest to the same angular speed of ω in this new configuration, how much work does the motor do on the rod in this case?
A rod is attached to the shaft of a motor at the center of the rod so that the rod is perpendicular to the shaft, as in figure a. The motor is turned on and performs a work W on the rod, accelerating it to an angular speed {image} . The system is brought to rest and the attachment to the rod is then moved along the shaft such that the rod is spun from its end instead, as in figure b. If the controls of the motor are adjusted such that the rod is accelerated from rest to the same angular speed of {image} in this new configuration, how much work does the motor do on the rod in this case? {image}
0.25 W
0.5 W
2 W
4 W

6. A ball rolls without slipping down incline A, starting from rest
A ball rolls without slipping down incline A, starting from rest. At the same time, a box starts from rest and slides down incline B, which is identical to incline A except it is frictionless. Which has a larger translational speed at the bottom of the ramp?
They have the same translational speed at the bottom of the ramp.
the ball
the box
It is impossible to determine.

7. Complete the following sentence: "The moment of inertia of an object
depends on the rotational speed of the object."
will be greater for a larger-massed object than for a smaller-massed object."
is not a function of the object's mass."
is a function of the axis about which the object is spun."

8. If you see an object rotating, is there necessarily a net nonzero torque acting on it?
yes.
only if it is rotating with a constant angular speed
No, a net nonzero torque would not cause an object to rotate.
only if the object's angular speed changes

9. Consider a solid sphere and a hollow sphere of the same radius, both made of material with the same density. They are both rotating on their axes with the same angular speed. Which one has the higher angular momentum?
the solid sphere
the hollow sphere
They both have the same angular momentum.
It is impossible to determine.

10. A skater rotates quickly on the ice. He pushes his arms out
A skater rotates quickly on the ice. He pushes his arms out. What happens to his angular speed?
It increases.
It decreases.
It stays the same.
It is impossible to determine.

11. A skater rotates quickly on the ice. He pushes his arms out
A skater rotates quickly on the ice. He pushes his arms out. What happens to his rotational kinetic energy?
It increases.
It decreases.
It stays the same.
It is impossible to determine.

12. If global warming were to occur over the next century, it is likely that some polar ice would melt, causing more water to be distributed evenly all over the Earth. What would happen to the length of the day as a result of this?
It would increase.
It would decrease.
Nothing, it would stay the same.
It is impossible to tell.

13. A popular demonstration involves a professor, initially motionless, standing on a low-friction turntable and holding a bicycle wheel that is spinning horizontally. What happens when the professor flips the bicycle wheel so that it is spinning in the other direction?
She starts to spin in the same direction as the initial direction of the bicycle wheel.
She starts to spin in the bicycle wheel's new spin direction.
She remains stationary.
It is impossible to tell because it depends on how fast the bicycle wheel initially spins.

14. Someone hits a tether ball to make it spin around a pole
Someone hits a tether ball to make it spin around a pole. The cord that attaches the tether ball to the central pole then winds around the pole. What happens to the angular speed of the tether ball during this process?
It decreases.
It increases.
It remains constant.
It cannot be determined.

15. If the torque acting on an object about a certain axis is zero, what can we say about the angular momentum of this object with respect to this axis?
It is zero.
It is constant.
It can never be zero.
Nothing, angular momentum has nothing to do with torque.

16. A single force acts on an object and the torque caused by the force is nonzero about some point. Is there any other point about which the torque is zero?
Yes, under any circumstance there is such a point.
No.
Yes, but only if the force is centripetal.
It is impossible to determine.

17. (i) only (i), (ii), and (iii) (ii) and (iii) only all of these
If an object were in torque equilibrium and in force equilibrium, could it (i) be stationary? (ii) move in a straight-line path? (iii) rotate in place? (iv) rotate while moving in a straight-line path?
(i) only
(i), (ii), and (iii)
(ii) and (iii) only
all of these

18. A 100 gram meter stick has a wad of clay on one end of it
A 100 gram meter stick has a wad of clay on one end of it. The stick is supported from a fulcrum point 33 1/3 cm from the clay. What is the clay's mass?
25 grams
50 grams
100 grams
200 grams

19. The center of gravity is a useful point at which to balance an object
The center of gravity is a useful point at which to balance an object. For instance, a ruler can be balanced by placing its center on your finger. Is it possible for the center of gravity of an object to be located at a point where no material exists to balance the object?
no, never
only for very unsymmetrical objects
It is possible in theory, but no objects have been found for which this occurs.
Yes, it is possible.

20. A tall crate and a short crate (both rectangular and of similar construction) of equal mass and equal base size are placed side by side on an incline, without touching each other. As the incline angle is increased, which crate will topple first?
the tall crate
the short crate
Both will topple at the same time.
It is impossible to tell, they will topple differently every time.