Physics Exam III Review
Chapter 7 – Rotational Motion and The Law of Gravity
1.
A rigid body is rotating counterclockwise about a fixed axis. The following pairs of quantities represent
an initial angular position and a final angular position of the rigid body. Which of the sets can only occur
if the rigid body rotates through more than 180 ? (
Quick quiz 7.1
)
a.
3 rad, 6 rad
b.
1 rad, 1 rad
c.
1 rad, 5 rad
2.
A race track is constructed such that two arcs of radium 80 m at A and 40 m at B are joined by two
stretches of straight track as in Figure 7.6. In a particular trial run, a driver traveled at a constant speed
of 50 m/s for one complete lap. (
Quick quiz 7.6
)
a.
What is the ratio of the tangential acceleration at A to that at B?
b.
What is the ratio of the centripetal acceleration at A to that at B?
c.
At which point is the angular speed greatest?
3.
An object moves in a circular path with constant speed
v
. What is happening to the velocity and
acceleration of the object? Are they constant or changing? (
Quick quiz 7.7
)
4.
As a ball drops and falls to the ground, which statements are false? (
Quick quiz 7.8
)
a.
The force that the ball exerts on Earth is equal in magnitude to the force that Earth exerts on the
ball.
b.
The ball undergoes the same acceleration as Earth.
c.
Earth is much more massive than the ball, so Earth pulls much harder on the ball than the ball
pulls on Earth. Thus, the ball falls while Earth remains stationary.
5.
A planet has two moons with identical mass. Moon 1 is in a circular orbit of radius
r
. Moon 2 is in a
circular orbit of radius 2
r
. The magnitude of the gravitational force exerted by the planet on Moon 2 is
(
Quick quiz 7.9
)
a.
Four times as large
b.
Twice as large
c.
The same
d.
Half as large
e.
Onefourth as large as the gravitational force exerted by the planet on Moon 1.
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 Spring '08
 Zerda
 Physics, Angular Momentum, Force, Gravity, Moment Of Inertia, Rotation

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