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HOLT PHYSICS
Section
7-1 Concept Review
Measuring Rotational Motion
1. Convert the following angles from degrees to radians.
a. 17.0°
c. 50.0°
e. –20.0°
b. 170.0°
d. 230.0°
f. 340.0°
2. Convert the following angles from radians to degrees.
a. 1.00 rad
c. –2.50 rad
e. 3.14 rad
b. 4.14 rad
d. 3.78 rad
f. 1.57 rad
3. A car moves forward 10.0 m in 1.5 s. Each tire rotates through an arc
length of 10.0 m, and each car tire has a radius of 3.5 × 10–1 m.
a. Find the angular displacement of one of the tires.
c. Assume the tire starts from rest and accelerates uniformly. Find the
angular acceleration of the tire.
d. What is the instantaneous angular speed of the tire after 1.5 s?
4. The period, T, of rotational motion is the time required for one com-
plete revolution, or the time for the object to rotate through 2p rad.
2pr
Starting with Dq = w Dt, show that T = .
v
34
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b. Find the average angular speed of the tire.
Rotational Motion and the Law of Gravity
Chapter
7
Section 7-1, p. 34
1. a. 0.297 rad
2. a. 57.3°
3. a. 29 rad
b. 2.967 rad
b. 237°
b. 19 rad/s
c. 0.873 rad
c. −143°
c. 25 rad/s2
d. 4.014 rad
d. 217°
d. 38 rad/s
2
e. −0.349 rad
e. (1.8 × 10 )°
f. 5.934 rad
f. 90.0°
4. w = v/r; ∆q = v∆t/r; ∆t = T if
∆q = 2p; 2p = vT/r; 2pr/v = T
Section 7-2, p. 35
1. a. 0.10 rad/s
3. 0.35 m/s2
2. a. 0.035 m/s
b. 0.50 rad/s
b. 0.18 m/s
c. 1.0 rad/s
c. 0.35 m/s
b. 0.5
d. 2.0 rad/s
d. 0.70 m/s
c. 2
e. 5.0 rad/s
e. 1.8 m/s
f. 1.0 × 101 rad/s
f. 3.5 m/s
4. a. 4
5. a. 18.8 m/s2
b. friction between tires and road
Section 7-3, p. 36
b. 4
III
c.
1

4
d. 1
1
c. double the radius, decrease the force to 4
d. If measured in the opposite direction, the force will
be in the opposite direction.
3. Because of inertia, objects tend to go in a straight line.
A force is needed to change the direction of travel.
2. a. double one mass, double the force
b. double both masses, quadruple the force
Chapter 7 Mixed Review
1. a. 3.0, 3.0, 9.0, 27
b. quadrupled
b. 4.3, 1.0, 4.3, 37
c. reduced to 4
c. 16, 0.28, 11, 6.0 × 102
d. quadrupled
d. 630, 0.11,74, 8.7
e. reduced to 9
e. 5.0, 44, 0.11, 9.9
2. a. friction
b. gravitational force
c. tension in string
3. a. doubled
1
1
4. 190 m
5. Student diagrams should show vectors for weight and
normal force from elevator; descent should show normal
force less than weight; stopping should show normal
force greater than weight; “weightlessness” feeling is due
to acceleration.
6. 1050 s (17.5 min)
III–8
Holt Physics Solution Manual
Copyright © by Holt, Rinehart and Winston. All rights reserved.
1. a. 2