What is the center of mass?
a. The exact middle of any object, measured from all its edges.
b. The location that the object would concentrate to if we imagined it to shrink to a point.
c. An arbitrarily chosen point in the object used to describe its motion.
d. A point in space that the object is moving toward.
e. A point in space to which an object is attracted.
[Ques. 2] When an object such as a monkey wrench is tossed into the air, the wrench:
a. translates around its center of mass while the center of mass rotates around a point in the wrench.
b. rotates around its center of mass while its center of mass undergoes translational motion.
c. undergoes rotational motion around an imaginary point in space.
d. undergoes either translational motion or rotational motion, not both.
e. undergoes translational motion that depends on the rotational motion around the center of mass.
[Ques. 3] When an object is spinning in place, it is experiencing:
a. projectile motion.
b. circular motion.
c. rotational motion.
d. vertical motion.
e. orbiting motion.
[Ques. 4] When an item has been launched into orbit:
a. it no longer falls because the weakening of Earth's gravity with increased height has made it lighter than air.
b. it no longer falls because it is outside the atmosphere.
c. it is kept in orbit by attraction to the Sun and Moon.
d. it continues to fall but its path never reaches the ground.
e. centripetal force from Earth's gravity keeps it from being accelerated toward Earth.
[Ques. 5] When something is thrown over large distances (on Earth), what new factor comes into play?
a. The curvature of the Earth.
b. The increase in gravity over long distances.
c. The decrease in gravity over long distances.
d. The tendency of thrown objects to fall to the ground.
e. The difference between miles and kilometers.
[Ques. 6] If there were no air resistance and no gravity:
a. an object thrown at an angle upward would come down, but more slowly than it does on Earth.
b. an object thrown at an angle upward would eventually change direction to move at constant height, rather than up.
c. an object thrown at an angle upward would come down the same way it does on Earth.
d. an object thrown at an angle upward would slow down and stop.
e. an object thrown at an angle upward would keep going up in the same direction for ever and never come down.
[Ques. 7] Why does banking (or tilting) a turning road create centripetal force?
a. Because banking the corner keeps cars from going too fast.
b. Because the angle of the roadway creates a centrifugal force.
c. Because the angle of the roadway creates a centripetal force.
d. Because the angle of the roadway helps cars counteract friction.
e. Because of friction.
[Ques. 8] Why does Michael Jordan appear to defy gravity as he slam dunks the ball? (After you have thought about this question, see page 68 of your textbook.)
a. He is an extraordinary athlete who is able to jump much higher than most humans.
b. His motion is that of a projectile, and a projectile's motion is such that its vertical speed is minimal while at the high point of its trajectory.
c. He is able to use air resistance to cushion his vertical motion.
d. He is in the process of moving upward.
e. His horizontal motion keeps him above the ground.
[Ques. 9] What happens to centripetal force when speed decreases, in the special case that the object continues moving in a circle of the same radius?
a. The force also decreases.
b. The force increases.
c. The radius cannot stay the same.
d. The force sometimes stays the same and sometimes decreases.
e. Speed does not affect centripetal force.
[Ques. 10] How do we calculate centripetal acceleration?
a. By calculating the acceleration at several points around the circle and averaging.
b. By subtracting two velocity vectors separated by a short time interval.
c. By adding two velocity vectors separated by a short time interval.
d. By calculating the change in speed.
e. By calculating the acceleration at several points around the circle and finding the sum.
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