Physics
Physics
1st Edition
Walker
ISBN: 9780133256925
Table of contents
Textbook solutions

All Solutions

Page 49: Practice Problems

Exercise 10
Solution 1
Solution 2
Step 1
1 of 2
The average speed equation is

$$
begin{align*}
text{average speed}=dfrac{text{distance}}{text{elapsed time}}\
end{align*}
$$

Rearranging the equation to solve for distance and plugging in the values, we obtain the result:

$$
begin{align*}
text{distance}&=text{average speed}timestext{elapsed time}\
&=4.6 frac{text{m}}{text{s}}times 1.4 text{s}\
&=quadboxed{6.4 text{m}}\
end{align*}
$$

Result
2 of 2
$$
begin{align*}
boxed{text{distance}=6.4 text{m}}\
end{align*}
$$
Step 1
1 of 2
$$
textbf{Concept:}
$$

Use equation to find the distance we get

$$
textbf{Solution:}
$$

$$
Distance=Avg.,Speed times elapsed,time
$$

Substituting the Numerical values we get…

$$
distance=(4.6frac{m}{cancel{s}})(1.4cancel{s})=color{#4257b2} boxed{bf 6.4m}
$$

Result
2 of 2
$$
distance=6.4m
$$
Exercise 11
Step 1
1 of 4
$text{underline{Answer in meters}}$

Using the equation for average speed, rearranging it to solve for distance, and plugging in the values, we get

$$
begin{align*}
text{average speed}&=dfrac{text{distance}}{text{elapsed time}}\
text{distance}&=text{average speed}timestext{elapsed time}\
&=340 frac{text{m}}{text{s}}times 3.5 text{s}\
&=quadboxed{1190 text{m}}\
end{align*}
$$

Step 2
2 of 4
$text{underline{Answer in kilometers}}$

The distance in kilometers is simply the distance in meters divided by 1000, as a meter is one thousandth of a kilometer,

$$
begin{align*}
boxed{text{distance}=1.190 text{km}}\
end{align*}
$$

Step 3
3 of 4
If you want a more detailed approach for the answer in kilometers, you can convert $frac{text{m}}{text{s}}$ to $frac{text{km}}{text{h}}$ and seconds to hours.

To convert $frac{text{m}}{text{s}}$ to $frac{text{km}}{text{h}}$, multiply the speed value by a conversion factor $left(dfrac{3.6 frac{text{km}}{text{h}}}{1 frac{text{m}}{text{s}}}right)$, and to convert seconds to hours, multiply the time value by $left(dfrac{1 text{h}}{3600 text{s}}right)$. Therefore,

$$
begin{align*}
text{distance}&=340 frac{text{m}}{text{s}}cdotleft(dfrac{3.6 frac{text{km}}{text{h}}}{1 frac{text{m}}{text{s}}}right)times 3.5 text{s}cdotleft(dfrac{1 text{h}}{3600 text{s}}right)\
&=1224 frac{text{km}}{text{h}}timesfrac{3.5 text{h}}{3600}\
&=quadboxed{1.19 text{km}}\
end{align*}
$$

In both cases, the final result is the same, but the first approach is more simple and straightforward.

Result
4 of 4
$$
begin{align*}
text{In kilometers:} quad &boxed{text{distance}=1190 text{m}}\
text{In meters:} quad &boxed{text{distance}=1.19 text{km}}\
end{align*}
$$
Exercise 12
Step 1
1 of 3
$textbf{(a)}$ We will again use the equation for average speed and solve it for time. However, we have to convert minutes to hours to get a dimensionally consistent result.

$$
begin{align*}
text{average speed}&=dfrac{text{distance}}{text{elapsed time}}\
text{distance}&=text{average speed}timestext{elapsed time}\
&=65 frac{text{km}}{text{h}}times 3.2 text{min}cdotleft(dfrac{1 text{h}}{60 text{min}}right)\
&=65 frac{text{km}}{text{h}}timesdfrac{3.2 text{h}}{60}\
&=quadboxed{3.5 text{km}}\
end{align*}
$$

Step 2
2 of 3
$textbf{(b)}$ Solving the same equation for the elapsed time and plugging in the values, we get

$$
begin{align*}
text{average speed}&=dfrac{text{distance}}{text{elapsed time}}\
text{elapsed time}&=dfrac{text{distance}}{text{average speed}}\
&=dfrac{0.25 text{km}}{65 frac{text{km}}{text{h}}}\
&=quadboxed{0.0038 text{h}}\
end{align*}
$$

When dealing with such small numbers, it’s more intuitive and makes more sense to write the result in appropriate order-of-magnitude units. For that reason, we’ll write the solution for elapsed time in seconds:

$$
begin{align*}
boxed{text{elapsed time}=14 text{s}}\
end{align*}
$$

Result
3 of 3
$$
begin{align*}
textbf{(a)} quad &boxed{text{distance}=3.5 text{km}}\
\
\
\
textbf{(b)} quad &boxed{text{elapsed time}=14 text{s}}\
end{align*}
$$
Exercise 13
Step 1
1 of 2
In order to find the average speed of the finch, first $textbf{we have to calculate the total distance it travelled.}$

$$
begin{align*}
text{distance}&=0.060 frac{text{m}}{text{s}}times 1.2 text{min}cdotleft(dfrac{60 text{s}}{1 text{min}}right)+13 frac{text{m}}{text{s}}times 1.2 text{min}cdotleft(dfrac{60 text{s}}{1 text{min}}right)\
&=quadboxed{940 text{m}}\
end{align*}
$$

$textbf{The average speed is the total distance travelled divided by the total time of motion}$

$$
begin{align*}
text{average speed}&=dfrac{text{total distance}}{text{total time}}\
\
\
\
&=dfrac{940 text{m}}{2.4 text{min}cdotleft(frac{60 text{s}}{1 text{min}}right)}\
\
\
\
&=quadboxed{6.5 frac{text{m}}{text{s}}}\
end{align*}
$$

Result
2 of 2
$$
begin{align*}
boxed{text{average speed}=6.5 frac{text{m}}{text{s}}}\
end{align*}
$$
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Chapter 1: Introduction to Physics
Section 1.1: Physics and the Scientific Method
Section 1.2: Physics and Society
Section 1.3: Units and Dimensions
Section 1.4: Basic Math for Physics
Page 38: Assessment
Page 41: Standardized Test Prep
Chapter 2: Introduction to Motion
Section 2.1: Describing Motion
Section 2.2: Speed and Velocity
Section 2.3: Position-Time Graphs
Section 2.4: Equation of Motion
Page 66: Assessment
Page 71: Standardized Test Prep
Page 45: Practice Problems
Page 47: Practice Problems
Page 47: Lesson Check
Page 49: Practice Problems
Page 52: Practice Problems
Page 53: Lesson Check
Page 56: Practice Problems
Page 57: Lesson Check
Page 59: Practice Problems
Page 60: Practice Problems
Page 62: Practice Problems
Page 62: Lesson Check
Chapter 3: Acceleration and Acceleration Motion
Section 3.1: Acceleration
Section 3.2: Motion with Constant Acceleration
Section 3.3: Position-Time Graphs for Constant Acceleration
Section 3.4: Free Fall
Page 105: Assessment
Page 111: Standardized Test Prep
Chapter 4: Motion in Two Dimensions
Section 4.1: Vectors in Physics
Section 4.2: Adding and Subtracting Vectors
Section 4.3: Relative Motion
Section 4.4: Projectile Motion
Page 144: Assessment
Page 149: Standardized Test Prep
Chapter 5: Newton’s Laws of Motion
Section 5.1: Newton’s Laws of Motion
Section 5.2: Applying Newton’s Laws
Section 5.3: Friction
Page 180: Assessment
Page 187: Standardized Test Prep
Chapter 6: Work and Energy
Section 6.1: Work
Section 6.2: Work and Energy
Section 6.3: Conservation of Energy
Section 6.4: Power
Page 220: Assessment
Page 227: Standardized Test Prep
Page 191: Practice Problems
Page 193: Practice Problems
Page 196: Lesson Check
Page 196: Practice Problems
Page 199: Practice Problems
Page 201: Practice Problems
Page 203: Practice Problems
Page 204: Practice Problems
Page 205: Practice Problems
Page 206: Lesson Check
Page 209: Practice Problems
Page 211: Lesson Check
Page 213: Practice Problems
Page 214: Practice Problems
Page 215: Practice Problems
Page 216: Lesson Check
Chapter 7: Linear Momentum and Collisions
Section 7.1: Momentum
Section 7.2: Impulse
Section 7.3: Conservation of Momentum
Section 7.4: Collisions
Page 260: Assessment
Page 265: Standardized Test Prep
Chapter 8: Rotational Motion and Equilibrium
Section 8.1: Describing Angular Motion
Section 8.2: Rolling Motion and the Moment of Inertia
Section 8.3: Torque
Section 8.4: Static Equilibrium
Page 300: Assessment
Page 305: Standardized Test Prep
Page 269: Practice Problems
Page 271: Practice Problems
Page 272: Practice Problems
Page 275: Practice Problems
Page 275: Lesson Check
Page 277: Practice Problems
Page 280: Lesson Check
Page 284: Practice Problems
Page 286: Practice Problems
Page 287: Practice Problems
Page 289: Lesson Check
Page 294: Practice Problems
Page 295: Practice Problems
Page 296: Lesson Check
Chapter 9: Gravity and Circular Motion
Section 9.1: Newton’s Law of Universal Gravity
Section 9.2: Applications of Gravity
Section 9.3: Circular Motion
Section 9.4: Planetary Motion and Orbits
Page 336: Assessment
Page 341: Standardized Test Prep
Chapter 10: Temperature and Heat
Section 10.1: Temperature, Energy, and Heat
Section 10.2: Thermal Expansion and Energy Transfer
Section 10.3: Heat Capacity
Section 10.4: Phase Changes and Latent Heat
Page 378: Assessment
Page 383: Standardized Test Prep
Chapter 11: Thermodynamics
Section 11.1: The First Law of Thermodynamics
Section 11.2: Thermal Processes
Section 11.3: The Second and Third Laws of Thermodynamics
Page 410: Assessment
Page 413: Standardized Test Prep
Chapter 12: Gases, Liquids, and Solids
Section 12.1: Gases
Section 12.2: Fluids at Rest
Section 12.3: Fluids in Motion
Section 12.4: Solids
Page 446: Assessment
Page 451: Standardized Test Prep
Chapter 13: Oscillations and Waves
Section 13.1: Oscillations and Periodic Motion
Section 13.2: The Pendulum
Section 13.3: Waves and Wave Properties
Section 13.4: Interacting Waves
Page 486: Assessment
Page 491: Standardized Test Prep
Chapter 14: Sound
Section 14.1: Sound Waves and Beats
Section 14.2: Standing Sound Waves
Section 14.3: The Doppler Effect
Section 14.4: Human Perception of Sound
Page 523: Assessment
Page 527: Standardized Test Prep
Page 495: Practice Problems
Page 496: Practice Problems
Page 500: Practice Problems
Page 501: Lesson Check
Page 503: Practice Problems
Page 504: Practice Problems
Page 506: Practice Problems
Page 506: Lesson Check
Page 510: Practice Problems
Page 511: Practice Problems
Page 512: Lesson Check
Page 514: Practice Problems
Page 516: Practice Problems
Page 517: Practice Problems
Page 519: Lesson Check
Chapter 15: The Properties of Lights
Section 15.1: The Nature of Light
Section 15.2: Color and the Electromagnetic Spectrum
Section 15.3: Polarization and Scattering of Light
Page 557: Assessment
Page 563: Standardized Test Prep
Chapter 16: Reflection and Mirrors
Section 16.1: The Reflection of Light
Section 16.2: Plane Mirrors
Section 16.3: Curved Mirrors
Page 590: Assessment
Page 595: Standardized Test Prep
Chapter 17: Refraction and Lenses
Section 17.1: Refraction
Section 17.2: Applications of Refraction
Section 17.3: Lenses
Section 17.4: Applications of Lenses
Page 629: Assessment
Page 635: Standardized Test Prep
Chapter 18: Interference and Diffraction
Section 18.1: Interference
Section 18.2: Interference in Thin Films
Section 18.3: Diffraction
Section 18.4: Diffraction Gratings
Page 668: Assessment
Page 673: Standardized Test Prep
Chapter 19: Electric Charges and Forces
Section 19.1: Electric Charge
Section 19.2: Electric Force
Section 19.3: Combining Electric Forces
Page 698: Assessment
Page 703: Standardized Test Prep
Chapter 20: Electric Fields and Electric Energy
Section 20.1: The Electric Field
Section 20.2: Electric Potential Energy and Electric Potential
Section 20.3: Capacitance and Energy Storage
Page 738: Assessment
Page 743: Standardized Test Prep
Chapter 21: Electric Current and Electric Circuits
Section 21.1: Electric Current, Resistance, and Semiconductors
Section 21.2: Electric Circuits
Section 21.3: Power and Energy in Electric Circuits
Page 775: Assessment
Page 781: Standardized Test Prep
Chapter 22: Magnetism and Magnetic Fields
Section 22.1: Magnets and Magnetic Fields
Section 22.2: Magnetism and Electric Currents
Section 22.3: The Magnetic Force
Page 810: Assessment
Page 815: Standardized Test Prep
Chapter 23: Electromagnetic Induction
Section 23.1: Electricity from Magnetism
Section 23.2: Electric Generators and Motors
Section 23.3: AC Circuits and Transformers
Page 844: Assessment
Page 849: Standardized Test Prep
Chapter 24: Quantum Physics
Section 24.1: Quantized Energy and Photons
Section 24.2: Wave-Particle Duality
Section 24.3: The Heisenberg Uncertainty Principle
Page 876: Assessment
Page 881: Standardized Test Prep
Chapter 26: Nuclear Physics
Section 26.1: The Nucleus
Section 26.2: Radioactivity
Section 26.3: Applications of Nuclear Physics
Section 26.4: Fundamental Forces and Elementary Particles
Page 944: Assessment
Page 947: Standardized Test Prep