How could the children in this photo best improve their balance with the help of two equal-mass weights?
a. Hold one weight in each hand with arms extended as shown in the photo.
b. Attach a weight to each ankle.
c. Place a weight in each of their left and right pockets in their trousers.
d. Hold one weight in each hand with arms held down instead of extended.
e. Hold one weight in each hand with one arm extended and one held down.
[Ques. 2] Which of the arrangements of the masses would enable the child to twirl the rod most easily, as might a cheerleader?
a. With the weights as far as possible from the middle.
b. With the weight as close to the middle as possible (assuming there was a convenient place to hold the rod with this arrangement).
c. The location of the masses would not affect the ability to easily twirl the rod.
[Ques. 3] If the net force applied to an object is zero, the net torque:
a. must also be zero.
b. can never be zero.
c. can sometimes be zero.
d. is not related to the net force.
e. can only be clockwise.
[Ques. 4] If the mother in this photo weighs four times as much as the child, where should she sit to keep the seesaw level if the child is seated at the far right hand side?
a. At the midpoint between the left end of the seesaw and the pivot point.
b. Halfway between the midpoint and the pivot point.
c. At the far left hand side of the seesaw.
d. One fourth of the distance from the pivot to the left end of the seesaw.
e. Halfway between the midpoint and the end of the left side of the seesaw.
[Ques. 5] Which of these is Newton's first law as applied to rotation?
a. In the absence of an external interaction, the angular displacement always remains constant.
b. In the presence of an external interaction, the angular velocity of an object changes.
c. In the absence of an external interaction, the angular velocity of an object remains constant.
d. In the presence of an external interaction, the angular velocity of an object remains constant.
e. Newton's first law applies only to translational motion, not rotation.
[Ques. 6] To open a very heavy door, the best place to push the door is:
a. half way between the doorknob and the hinge.
b. at the end of the door where the doorknob is located.
c. torque, not force, is what matters. Hence, it makes no difference where the force is applied.
d. near the bottom of the door.
e. close to the hinges.
[Ques. 7] What is the agreed-upon direction of rotational velocity?
a. The direction the object is rotating (effectively clockwise).
b. In the direction opposite to the way the object is rotating (effectively counterclockwise).
c. Along the axis of rotation in the direction your thumb would point if the fingers of your left hand curl along the motion of the spinning object.
d. Along the axis of rotation in the direction your thumb would point if the fingers of your right hand curl along the motion of the spinning object.
e. Along the axis of rotation in the direction your index finger would point if the thumb of your right hand points along the motion of the spinning object.
[Ques. 8] Rotational acceleration measures:
a. the rate at which rotational speed changes.
b. rotational speed.
c. angular momentum.
d. the rate at which angular position changes.
e. rotational energy.
[Ques. 9] Translational (linear) speed is displacement divided by time, and rotational speed is:
a. the same thing.
b. angular displacement divided by time.
c. rotational acceleration divided by time.
d. the distance along the edge of a rotating disk divided by time.
e. translational speed divided by displacement.
[Ques. 10] Assuming that no energy is lost in the form of heat, after the ball compresses the spring shown here, what is the maximum potential energy it may once again attain?
a. 0 J.
b. 5 J.
c. 2.5 J.
d. Significantly less than 5 J because of energy lost as heat because of friction.
e. Significantly less than 2.5 J because of energy lost as heat because of friction.
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