Physics: Principles and Problems
Physics: Principles and Problems
9th Edition
Elliott, Haase, Harper, Herzog, Margaret Zorn, Nelson, Schuler, Zitzewitz
ISBN: 9780078458132
Table of contents
Textbook solutions

All Solutions

Page 200: Practice Problems

Exercise 1
Solution 1
Solution 2
Step 1
1 of 4
We need to calculate the angular displacement in a period of one hour for each of the hands on the clock. Hour hand. minute hand and second hand.
Step 2
2 of 4
In order to calculate angular displacement, we need to calculate how many $textbf{rotations}$ each hand makes in a period of $textbf{one }$hour:

$textbf{Second hand will make 60 complete rotations}$. One each minute and there are 60 minutes in one hour.

$textbf{Minute hand will make 1 complete rotation}$ in a period of one hour,

$textbf{Hour hand will make 1/12 complete rotations }$since it will move for one out of twelve hours marked on a clock in a period of one hour, which means it will make $frac{1}{12}$ complete rotations in one hour.

Step 3
3 of 4
In 1 hour, the second hand will have 60 complete rotations in the clockwise direction:

$$
Delta_{theta s}=60cdot (-2cdotpi )=-377,,rm{rad}
$$

In 1 hour, the minute hand will have 1 complete rotation in the clockwise direction:

$$
Delta_{theta m}=1cdot (-2cdotpi )=-6.28,,rm{rad}
$$

In 1 hour, the hour hand will have $frac{1}{12}$ complete rotations in the clockwise direction:

$$
Delta_{theta h}=frac{1}{12} cdot (-2cdotpi )=-0.524,,rm{rad}
$$

Result
4 of 4
$$
Delta_{theta s}=-377,,rm{rad}
$$

$$
Delta_{theta m}=-6.28,,rm{rad}
$$

$$
Delta_{theta h}=-0.524,,rm{rad}
$$

Step 1
1 of 2
a)

In 1 hour the second hand have 60 complete rotations in the clockwise direction:

$Delta theta = (60) (-2pi) = -120 pi rad = -377 rad$

b)

In 1 hour the minute hand have 1 complete rotations in the clockwise direction:

$Delta theta = (1) (-2pi) = -2 pi rad = -6.28 rad$

c)

In 1 hour the hour hand have $dfrac{1}{12}$ of a complete rotations in the clockwise direction:

$$
Delta theta = (dfrac{1}{12}) (-2pi) = -pi/6 rad = -0.524 rad
$$

Result
2 of 2
a) $-377 rad$

b) $-6.28 rad$

c) $-0.524 rad$

Exercise 2
Solution 1
Solution 2
Step 1
1 of 5
We need to calculate diameter of the wheels. The information that we are given is linear acceleration:

$$
a=1.85,,rm{m/s^2},
$$

and angular acceleration:

$$
alpha =5.23,,rm{rad/s^2}
$$

Step 2
2 of 5
Just as angular velocity and linear velocity are connected, so are angular acceleration and linear acceleration through the next equation:

$$
a =alpha cdot frac{d}{2}
$$

Step 3
3 of 5
From the previous equation we can get:

$$
d=frac{2cdot a}{alpha}
$$

Step 4
4 of 5
When we insert values we get:

$$
d=frac{2cdot 1.85}{5.23}=0.707,,rm{m}
$$

Result
5 of 5
$$
d=0.707,,rm{m}
$$
Step 1
1 of 2
The radius of the wheels is:

$r = dfrac{a}{alpha} = dfrac{1.85}{5.23} = 0.3537 m$

The diameter of the wheels is:

$$
d = 2 r = 0.707 m
$$

Result
2 of 2
$$
0.707 m
$$
Exercise 3
Step 1
1 of 5
Truck from the previous problem is towing a trailer with diameter of wheels of:

$$
d=0.48,,rm{m}
$$

Wheels on the truck have diameter of:

$$
d_t=0.707,,rm{m}
$$

Linear acceleration of the truck is:

$$
a_t=1.85,,rm{m/s^2}
$$

And angular acceleration of the wheels on the truck was:

$$
alpha_t=5.23,,rm{rad/s^2}
$$

Step 2
2 of 5
a) While towing a trailer, between a truck and trailer is a fixed connection maintaining always constant distance between them. This means that displacement of the truck is equal to that of the trailer. Which further means that so is linear velocity as well as linear acceleration. That means that:

$$
a=a_t=1.85,,rm{m/s^2}
$$

Step 3
3 of 5
b) Since we know that their linear acceleration is equal, we can use the equation that connects linear and angular acceleration in order to compare them:

$$
a=alpha cdot 0.5cdot d
$$

$$
alpha =frac{a}{0.5cdot d}
$$

Step 4
4 of 5
First, lets compare linear accelerations:

$$
a=a_t
$$

Inserting previous equation we get:

$$
alpha cdot 0.5cdot d=alpha_t cdot 0.5cdot d_t
$$

By solving equation we get:

$$
frac{alpha}{alpha_t}=frac{d_t}{d}
$$

Inserting value we get:

$$
frac{alpha}{alpha_t}=frac{0.707}{0.48}=1.47
$$

Result
5 of 5
$$
a=1.85,,rm{m/s^2}
$$

$$
frac{alpha}{alpha_t}=1.47
$$

Exercise 4
Step 1
1 of 3
Assuming constant velocity and linear distance, we need to find out how do the angular velocity and number of revolutions change with change in tire diameter.
Step 2
2 of 3
Angular velocity can be expressed as:

$$
omega =frac{v}{0.5cdot d}
$$

And distance traveled ($s$) can be expressed through number of revolutions ($n$) as:

$$
s=ncdot dcdot pi
$$

With constant distance we get:

$$
n=frac{s}{dcdot pi}
$$

Step 3
3 of 3
From the previous equations we can conclude that by $textbf{increasing diameter}$, both angular velocity and number of revolutions will $textbf{decrease}$.
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Section 1.2: Measurement
Section 1.3: Graphing Data
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Page 29: Standardized Test Practice
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Section 3.2: Motion with Constant Acceleration
Section 3.3: Free Fall
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Section 4.2: Using Newton’s Laws
Section 4.3: Interaction Forces
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Section 7.2: Using the Law of Universal Gravitation
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Section 8.1: Describing Rotational Motion
Section 8.2: Rotational Dynamics
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Page 227: Standardized Test Practice
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Chapter 10: Energy, Work, and Simple Machines
Section 10.1: Energy and Work
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Page 283: Standardized Test Practice
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Page 311: Standardized Test Practice
Chapter 13: State of Matter
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Section 13.2: Forces Within Liquids
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