The axis of rotation of a top changes its direction as the top spins because:
a. the inertia of the top keeps its orientation changing.
b. conservation of rotational motion keeps the direction changing if it was changing to start.
c. rotational kinetic energy causes the direction to shift.
d. gravitational force exerts torque on the top.
e. angular momentum is conserved.
[Ques. 2] Which of the following would make the demonstration illustrated in this figure function less effectively?
a. Use a piece of cardboard with a greater mass.
b. Use a piece of cardboard with a greater radius.
c. Use a piece of cardboard with less mass and smaller radius.
d. Use a thinner pencil.
e. Use a thicker pencil.
[Ques. 3] Which of these is NOT a vector quantity?
a. translational momentum
b. angular momentum
c. acceleration
d. rotational kinetic energy
e. velocity
[Ques. 4] Which of the following is true about how the planets revolve around the Sun and how the Sun rotates?
a. There is no pattern to the rotation of all these bodies.
b. The planets all revolve in one direction and the Sun rotates on its axis in the other direction.
c. The planets revolve around the Sun in the same direction that the Sun rotates.
d. The Sun rotates on its axis in the opposite direction from the revolution of the planets and thus angular momentum is conserved.
e. The Sun does not rotate, but the planets all revolve around it in the same direction.
[Ques. 5] Which position of the diver's body results in the most rapid spinning?
a. Position a.
b. Position b.
c. Position c.
d. Both a. and c.
e. The spin rate is the same speed for all three because of momentum conservation.
[Ques. 6] The angular momentum of a particle moving in a circle around a point is equal to:
a. half of the rotational inertia times the square of the rotational speed.
b. the mass times the speed of the particle times the radius of its orbit.
c. the sum of its kinetic and potential energies.
d. half its mass times the square of its speed.
e. its mass times its velocity.
[Ques. 7] Which is the correct expression for rotational kinetic energy?
a. Half of the rotational inertia times the square of the rotational speed.
b. The mass times the speed times the radius.
c. The mass times velocity.
d. Half of the mass times the square of the speed.
e. The force times the distance.
[Ques. 8] Stable equilibrium is:
a. an equilibrium state where any small rotation results in a torque that acts to produce rotation back in the opposite direction.
b. any form of equilibrium, because all equilibrium conditions are stable.
c. an equilibrium state where nothing is moving.
d. an equilibrium state where there is no net torque or net force.
e. an equilibrium state where no torque is involved.
[Ques. 9] If an object is hollow, where is its center of mass?
a. At the nearest point nearest the center where mass can be found.
b. At the center, even though there is no mass actually there.
c. Halfway between the hollow center and the nearest point where there is mass.
d. All along the outer shell of the hollow object.
e. At the point between the center and the edge where the average mass along that line is greatest.
[Ques. 10] If the shafts on the two gears shown in this figure had the same diameter, but were made of different materials, which shaft should be made of the stronger material to avoid breakage? (Hint: The torque exerted on each shaft must be the same as the torque on the gear to which it is attached.)
a. The shaft on the smaller gear since it must compensate for the smaller size of the gear.
b. The torques on the two shafts will always be the same, so it does not matter.
c. The shaft on the larger gear since it will have to withstand a greater torque.
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