,1 | What Is Physics? 1
1 | WHAT IS PHYSICS?
The Instructor Answer Guide for Physics contains the worked-out answers to questions that
appear at the end of each chapter. Grasp Check Questions, which occur in the body text of
sections, and Practice Problems and Check Your Understanding exercises, which occur at the
end of sections, are not included in the Instructor Answer Guide for this book.
CHAPTER REVIEW
Concept Items
1.1 Physics: Definitions and Applications
1 Which statement best compares and contrasts the aims and topics of natural philosophy
versus physics?
A Natural philosophy included all aspects of nature including physics.
B Natural philosophy included all aspects of nature excluding physics.
C Natural philosophy and physics are different.
D Natural philosophy and physics are essentially the same thing.
Solution The correct answer is (A). Natural philosophy included all aspects of nature by
lumping physics in with other fields of science, such as chemistry and biology. Now,
physics mainly describes the most fundamental aspects of our universe, such as
motion, energy, matter, and space.
2 Which statement is NOT an underlying assumption essential to scientific understandings?
A Characteristics of the physical universe can be perceived and objectively measured by
human beings.
B Explanations of natural phenomena can be established with absolute certainty.
C Fundamental physical processes dictate how characteristics of the physical universe
evolve.
D The fundamental processes of nature operate the same way everywhere and at all
times.
Solution The correct answer is (B). Scientific explanations may be supported by all available
evidence at a particular point in time, but science never precludes the possibility
that some future observation could contradict the explanation, requiring a
modification to the existing explanation or an entirely new explanation.
3 Which question regarding a strain of genetically modified rice is NOT one that science can
answer?
A How does the yield of the genetically modified rice compare with that of existing rice?
B Is the genetically modified rice more resistant to infestation than existing rice?
Physics Instructor’s Solution Manual
,1 | What Is Physics? 2
C How does the nutritional value of the genetically modified rice compare to that of
existing rice?
D Should the genetically modified rice be grown commercially and sold in the
marketplace?
Solution The correct answer is (D). Administrators need to make a judgment call based on
scientific evidence regarding the safety and commercial viability of the genetically
modified rice.
4 What conditions imply that we can use classical physics without considering special
relativity or quantum mechanics?
A 1. Matter is moving at speeds of less than roughly 1 percent the speed of light.
2. Objects are large enough to be seen with the naked eye.
3. There is the involvement of a strong gravitational field.
B 1. Matter is moving at speeds greater than roughly 1 percent the speed of light.
2. Objects are large enough to be seen with the naked eye.
3. There is the involvement of a strong gravitational field.
C 1. Matter is moving at speeds of less than roughly 1 percent the speed of light.
2. Objects are too small to be seen with the naked eye.
3. There is the involvement of only a weak gravitational field.
D 1. Matter is moving at speeds of less than roughly 1 percent the speed of light.
2. Objects are large enough to be seen with the naked eye.
3. There is the involvement of a weak gravitational field.
Solution The correct answer is (D). The conditions that must be met include: (1) matter must
be moving at speeds less than about 1 percent of the speed of light; (2) microscopic
(not subatomic) particles as well as those visible with the naked eye; (3) only weak
gravitational fields, such as the field generated by Earth, can be involved.
5 How could physics be useful in weather prediction?
A Physics helps predict how burning fossil fuel releases pollutants.
B Physics helps predict dynamics and movement of weather phenomena.
C Physics helps predict the motion of tectonic plates.
D Physics helps predict how the flowing water affects Earth’s surface.
Solution The correct answer is (B). Physics is useful in weather prediction because the
physical laws of motion and energy govern the movement of air masses and energy
in our atmosphere, which is what generates weather.
6 How do physical therapists use physics while on the job? Explain.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 3
A Physical therapists do not require knowledge of physics because their job is mainly
therapy and not physics.
B Physical therapists do not require knowledge of physics because their job is more
social in nature and unscientific.
C Physical therapists require knowledge of physics to know about muscle contraction
and release of energy.
D Physical therapists require knowledge of physics to know about chemical reactions
inside the body and make decisions accordingly.
Solution The correct answer is (C). Physical therapists must understand how muscles
generate forces that allow the body to move and bend. Physics allows us to
understand this.
7 What is meant when a physical law is said to be universal?
A The law can explain everything in the universe.
B The law is applicable to all physical phenomena.
C The law applies everywhere in the universe.
D The law is the most basic one and all laws are derived from it.
Solution The correct answer is (C). A universal law is one that explains a specific physics
phenomenon, such as how the force of gravity is based on the mass of an object and
that object’s distance from another object. To be universal, this law should apply
everywhere in the universe.
8 What subfield of physics could describe small objects traveling at high speeds or
experiencing a strong gravitational field?
A General theory of relativity
B Classical physics
C Quantum relativity
D Special theory of relativity
Solution The correct answer is (C). Quantum relativity describes small objects traveling at
high speeds or experiencing a strong gravitational field.
9 Why is Einstein’s theory of relativity considered part of modern physics, as opposed to
classical physics?
A Because it is considered less outstanding than the classics of physics, such as classical
mechanics
B Because popular physics is enjoyed by average people today, instead of physics
studied by the elite
C Because the theory deals with very slow-moving objects and weak gravitational fields
Physics Instructor’s Solution Manual
,1 | What Is Physics? 4
D Because it was among the new 19th-century discoveries that changed physics
Solution The correct answer is (D). Einstein’s theory of relativity is considered part of modern
physics because it was developed alongside other far-reaching scientific advances in
the 19th century. These advances radically changed ideas in physics from those
accepted in the previous (classical) period dominated by Newton and Galileo.
1.2 The Scientific Methods
10 What is the difference between an observation and a hypothesis?
A An observation is seeing what happens; a hypothesis is a testable, educated guess.
B An observation is a hypothesis that has been confirmed.
C Hypotheses and observations are independent of each other.
D Hypotheses are conclusions based on some observations.
Solution The correct answer is (A). An observation is a pattern or trend that a person sees in
nature while a hypothesis is an educated guess that attempts to explain something
about the observation.
11 How is modeling useful in studying the structure of the atom?
A Modeling replaces the real system with something similar but easier to examine.
B Modeling replaces the real system with something more interesting to examine.
C Modeling replaces the real system with something with more realistic properties.
D Modeling includes more details than are present in the real system.
Solution The correct answer is (A). Modeling is useful in studying the structure of the atom
because models replace the real atom with something simpler that has similar
features and similar expected behavior.
12 How strongly is a hypothesis supported by evidence compared to a theory?
A A theory is supported by little evidence, if any, at first. A hypothesis is supported by a
large amount of available evidence.
B A hypothesis is supported by little evidence, if any, at first. A theory is supported by a
large amount of available evidence.
C A hypothesis is supported by little evidence, if any, at first. A theory does not need any
experiments for support.
D A theory is supported by little evidence, if any, at first. A hypothesis does not need any
experiments for support.
Solution The correct answer is (B). A hypothesis is an experimental test and doesn’t
necessarily need much evidence to prove the case. A theory, however, has been
proven and needs to be supported so that any retrial shows that same theory holds
true.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 5
1.3 The Language of Physics: Physical Quantities and Units
13 Which option does NOT contribute to uncertainty?
A The limitations of the measuring device
B The skill of the person making the measurement
C The regularities in the object being measured
D Other factors that affect the outcome (depending on the situation)
Solution The correct answer is (C). The object itself is what it is made of and does not take a
skill in measurements like the rest of the choices.
14 How does the independent variable in a graph differ from the dependent variable?
A The dependent variable varies linearly with the independent variable.
B The dependent variable depends on the scale of the axis chosen, while the
independent variable does not.
C The independent variable is directly manipulated or controlled by the person doing
the experiment, while dependent variable is the one that changes as a result.
D The dependent and independent variables are fixed by convention; hence, they are
the same.
Solution The correct answer is (C). The independent variable does not change as a result of
changes in the dependent variable. The dependent variable, on the other hand, does
change as a result of changes in the independent variable.
15 What could you conclude about these two lines?
Line A has a slope of .
Line B has a slope of 12.0.
A Line A is decreasing while line B is increasing, with line A being much steeper than
line B.
B Line A is decreasing while line B is increasing, with line B being much steeper than
line A.
C Line B is decreasing while line A is increasing, with line A being much steeper than
line B.
D Line B is decreasing while line A is increasing, with line B being much steeper than
line A.
Solution The correct answer is (B). You could conclude that line A is decreasing while line B is
increasing, with line B being much steeper than line A.
16 Velocity, or speed, is measured using the formula
Physics Instructor’s Solution Manual
,1 | What Is Physics? 6
,
where v is velocity, d is the distance traveled, and t is the time the object took to travel the
distance.
If the velocity-time data are plotted on a graph, which variable will be on which
axis? Why?
A Time would be on the x-axis and velocity on the y-axis, because time is an
independent variable and velocity is a dependent variable.
B Velocity would be on the x-axis and time on the y-axis, because time is the
independent variable and velocity is the dependent variable.
C Time would be on the x-axis and velocity on the y-axis, because time is a dependent
variable and velocity is an independent variable.
D Velocity would be on the x-axis and time on the y-axis, because time is a dependent
variable and velocity is an independent variable.
Solution The correct answer is (A). Time would be on the x-axis and distance would be on the
y-axis, because time passes independently of how far the car travels. Therefore, time
is the independent variable while distance is the dependent variable.
17 A good-quality measuring tape can be off by 0.50 cm over a distance of 20 m. What is its
percent uncertainty in scientific notation?
A
B
C
D
Solution The correct answer is (A).
18 What is the definition of uncertainty?
A Uncertainty is the number of assumptions made prior to the measurement of a
physical quantity.
B Uncertainty is a measure of error in a measurement due to the use of a noncalibrated
instrument.
C Uncertainty is a measure of deviation of the measured value from the standard value.
D Uncertainty is a measure of error in measurement due to external factors like air
friction and temperature.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 7
Solution The correct answer is (C). Uncertainty is a quantitative measure of how much your
measured values deviate from a standard or expected value.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 8
Critical Thinking Items
1.1 Physics: Definitions and Applications
19 In what sense does Einstein’s theory of relativity illustrate that physics describes
fundamental aspects of our universe?
A It describes how speed affects different observers’ measurements of time and space.
B It describes how different parts of the universe are far apart and do not affect each
other.
C It describes how people think of other people’s views from their own frame of
reference.
D It describes how a frame of reference is necessary to describe position or motion.
Solution The correct answer is (A). According to Einstein's theory of relativity, gravity or the
speed of the observer can affect what they observe as measured time intervals and
measured distances, as occurs with length contraction or time dilation.
20 Yes or no—Can classical physics be used to accurately describe a satellite moving at a
speed of ? Explain why or why not.
A No, because the satellite is moving at a speed much slower than the speed of the light
and is not in a strong gravitational field
B No, because the satellite is moving at a speed much slower than the speed of the light
and is in a strong gravitational field
C Yes, because the satellite is moving at a speed much slower than the speed of the light
and it is not in a strong gravitational field
D Yes, because the satellite is moving at a speed much slower than the speed of the light
and is in a strong gravitational field
Solution The correct answer is (C). Yes, classical physics could describe the motion of a
satellite, because it is moving at a speed much slower than the speed of light,
because it is not in a strong gravitational field, and because it involves an object that
is visible to the naked eye.
21 What would be some ways in which physics was involved in building the features of the
room you are in right now?
A Physics is involved in the structural strength and dimensions of the room.
B Physics is involved in the air composition inside the room.
C Physics is involved in the desk arrangement inside the room.
D Physics is involved in the behavior of living beings inside the room.
Solution The correct answer is (A). The physics of gravity, weight, and forces was used to
design the walls, ceilings, and floors in the room so they could hold up people and
Physics Instructor’s Solution Manual
, 1 | What Is Physics? 9
furniture. Knowledge of physics involving electricity went into developing lighting,
fans, electrical outlets, and other electrical devices in the room.
22 What theory of modern physics describes the interrelationships between space, time,
speed, and gravity?
A Atomic theory
B Nuclear physics
C Quantum mechanics
D General relativity
Solution The correct answer is (D). Einstein came up with general relativity to explain how
gravity is a result of bending of space and time.
23 According to Einstein’s theory of relativity, how could you effectively travel many years
into Earth’s future, but not age very much yourself?
A By traveling at a speed equal to the speed of light
B By traveling at a speed faster than the speed of light
C By traveling at a speed much slower than the speed of light
D By traveling at a speed slightly slower than the speed of light
Solution The correct answer is (D). You could do this by traveling away from Earth at near the
speed of light, because measured time intervals are shorter in the frame of
reference of the spaceship, in which you are at rest, than measured from Earth,
where you are seen as moving.
1.2 The Scientific Methods
24 You notice that the water level flowing in a stream near your house increases when it
rains and the water turns brown. Which hypothesis best explains why the water turns
brown? Assume you have all of the means to test the contents of the stream water.
A The water in the stream turns brown because molecular forces between water
molecules are stronger than mud molecules.
B The water in the stream turns brown because of the breakage of a weak chemical
bond with the hydrogen atom in the water molecule.
C The water in the stream turns brown because it picks up dirt from the bank as the
water level increases when it rains.
D The water in the stream turns brown because the density of the water increases with
increase in water level.
Solution The correct answer is (C). The brown color of water comes from the dirt that is
picked up from the edges of the banks of the water.
Physics Instructor’s Solution Manual
1 | WHAT IS PHYSICS?
The Instructor Answer Guide for Physics contains the worked-out answers to questions that
appear at the end of each chapter. Grasp Check Questions, which occur in the body text of
sections, and Practice Problems and Check Your Understanding exercises, which occur at the
end of sections, are not included in the Instructor Answer Guide for this book.
CHAPTER REVIEW
Concept Items
1.1 Physics: Definitions and Applications
1 Which statement best compares and contrasts the aims and topics of natural philosophy
versus physics?
A Natural philosophy included all aspects of nature including physics.
B Natural philosophy included all aspects of nature excluding physics.
C Natural philosophy and physics are different.
D Natural philosophy and physics are essentially the same thing.
Solution The correct answer is (A). Natural philosophy included all aspects of nature by
lumping physics in with other fields of science, such as chemistry and biology. Now,
physics mainly describes the most fundamental aspects of our universe, such as
motion, energy, matter, and space.
2 Which statement is NOT an underlying assumption essential to scientific understandings?
A Characteristics of the physical universe can be perceived and objectively measured by
human beings.
B Explanations of natural phenomena can be established with absolute certainty.
C Fundamental physical processes dictate how characteristics of the physical universe
evolve.
D The fundamental processes of nature operate the same way everywhere and at all
times.
Solution The correct answer is (B). Scientific explanations may be supported by all available
evidence at a particular point in time, but science never precludes the possibility
that some future observation could contradict the explanation, requiring a
modification to the existing explanation or an entirely new explanation.
3 Which question regarding a strain of genetically modified rice is NOT one that science can
answer?
A How does the yield of the genetically modified rice compare with that of existing rice?
B Is the genetically modified rice more resistant to infestation than existing rice?
Physics Instructor’s Solution Manual
,1 | What Is Physics? 2
C How does the nutritional value of the genetically modified rice compare to that of
existing rice?
D Should the genetically modified rice be grown commercially and sold in the
marketplace?
Solution The correct answer is (D). Administrators need to make a judgment call based on
scientific evidence regarding the safety and commercial viability of the genetically
modified rice.
4 What conditions imply that we can use classical physics without considering special
relativity or quantum mechanics?
A 1. Matter is moving at speeds of less than roughly 1 percent the speed of light.
2. Objects are large enough to be seen with the naked eye.
3. There is the involvement of a strong gravitational field.
B 1. Matter is moving at speeds greater than roughly 1 percent the speed of light.
2. Objects are large enough to be seen with the naked eye.
3. There is the involvement of a strong gravitational field.
C 1. Matter is moving at speeds of less than roughly 1 percent the speed of light.
2. Objects are too small to be seen with the naked eye.
3. There is the involvement of only a weak gravitational field.
D 1. Matter is moving at speeds of less than roughly 1 percent the speed of light.
2. Objects are large enough to be seen with the naked eye.
3. There is the involvement of a weak gravitational field.
Solution The correct answer is (D). The conditions that must be met include: (1) matter must
be moving at speeds less than about 1 percent of the speed of light; (2) microscopic
(not subatomic) particles as well as those visible with the naked eye; (3) only weak
gravitational fields, such as the field generated by Earth, can be involved.
5 How could physics be useful in weather prediction?
A Physics helps predict how burning fossil fuel releases pollutants.
B Physics helps predict dynamics and movement of weather phenomena.
C Physics helps predict the motion of tectonic plates.
D Physics helps predict how the flowing water affects Earth’s surface.
Solution The correct answer is (B). Physics is useful in weather prediction because the
physical laws of motion and energy govern the movement of air masses and energy
in our atmosphere, which is what generates weather.
6 How do physical therapists use physics while on the job? Explain.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 3
A Physical therapists do not require knowledge of physics because their job is mainly
therapy and not physics.
B Physical therapists do not require knowledge of physics because their job is more
social in nature and unscientific.
C Physical therapists require knowledge of physics to know about muscle contraction
and release of energy.
D Physical therapists require knowledge of physics to know about chemical reactions
inside the body and make decisions accordingly.
Solution The correct answer is (C). Physical therapists must understand how muscles
generate forces that allow the body to move and bend. Physics allows us to
understand this.
7 What is meant when a physical law is said to be universal?
A The law can explain everything in the universe.
B The law is applicable to all physical phenomena.
C The law applies everywhere in the universe.
D The law is the most basic one and all laws are derived from it.
Solution The correct answer is (C). A universal law is one that explains a specific physics
phenomenon, such as how the force of gravity is based on the mass of an object and
that object’s distance from another object. To be universal, this law should apply
everywhere in the universe.
8 What subfield of physics could describe small objects traveling at high speeds or
experiencing a strong gravitational field?
A General theory of relativity
B Classical physics
C Quantum relativity
D Special theory of relativity
Solution The correct answer is (C). Quantum relativity describes small objects traveling at
high speeds or experiencing a strong gravitational field.
9 Why is Einstein’s theory of relativity considered part of modern physics, as opposed to
classical physics?
A Because it is considered less outstanding than the classics of physics, such as classical
mechanics
B Because popular physics is enjoyed by average people today, instead of physics
studied by the elite
C Because the theory deals with very slow-moving objects and weak gravitational fields
Physics Instructor’s Solution Manual
,1 | What Is Physics? 4
D Because it was among the new 19th-century discoveries that changed physics
Solution The correct answer is (D). Einstein’s theory of relativity is considered part of modern
physics because it was developed alongside other far-reaching scientific advances in
the 19th century. These advances radically changed ideas in physics from those
accepted in the previous (classical) period dominated by Newton and Galileo.
1.2 The Scientific Methods
10 What is the difference between an observation and a hypothesis?
A An observation is seeing what happens; a hypothesis is a testable, educated guess.
B An observation is a hypothesis that has been confirmed.
C Hypotheses and observations are independent of each other.
D Hypotheses are conclusions based on some observations.
Solution The correct answer is (A). An observation is a pattern or trend that a person sees in
nature while a hypothesis is an educated guess that attempts to explain something
about the observation.
11 How is modeling useful in studying the structure of the atom?
A Modeling replaces the real system with something similar but easier to examine.
B Modeling replaces the real system with something more interesting to examine.
C Modeling replaces the real system with something with more realistic properties.
D Modeling includes more details than are present in the real system.
Solution The correct answer is (A). Modeling is useful in studying the structure of the atom
because models replace the real atom with something simpler that has similar
features and similar expected behavior.
12 How strongly is a hypothesis supported by evidence compared to a theory?
A A theory is supported by little evidence, if any, at first. A hypothesis is supported by a
large amount of available evidence.
B A hypothesis is supported by little evidence, if any, at first. A theory is supported by a
large amount of available evidence.
C A hypothesis is supported by little evidence, if any, at first. A theory does not need any
experiments for support.
D A theory is supported by little evidence, if any, at first. A hypothesis does not need any
experiments for support.
Solution The correct answer is (B). A hypothesis is an experimental test and doesn’t
necessarily need much evidence to prove the case. A theory, however, has been
proven and needs to be supported so that any retrial shows that same theory holds
true.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 5
1.3 The Language of Physics: Physical Quantities and Units
13 Which option does NOT contribute to uncertainty?
A The limitations of the measuring device
B The skill of the person making the measurement
C The regularities in the object being measured
D Other factors that affect the outcome (depending on the situation)
Solution The correct answer is (C). The object itself is what it is made of and does not take a
skill in measurements like the rest of the choices.
14 How does the independent variable in a graph differ from the dependent variable?
A The dependent variable varies linearly with the independent variable.
B The dependent variable depends on the scale of the axis chosen, while the
independent variable does not.
C The independent variable is directly manipulated or controlled by the person doing
the experiment, while dependent variable is the one that changes as a result.
D The dependent and independent variables are fixed by convention; hence, they are
the same.
Solution The correct answer is (C). The independent variable does not change as a result of
changes in the dependent variable. The dependent variable, on the other hand, does
change as a result of changes in the independent variable.
15 What could you conclude about these two lines?
Line A has a slope of .
Line B has a slope of 12.0.
A Line A is decreasing while line B is increasing, with line A being much steeper than
line B.
B Line A is decreasing while line B is increasing, with line B being much steeper than
line A.
C Line B is decreasing while line A is increasing, with line A being much steeper than
line B.
D Line B is decreasing while line A is increasing, with line B being much steeper than
line A.
Solution The correct answer is (B). You could conclude that line A is decreasing while line B is
increasing, with line B being much steeper than line A.
16 Velocity, or speed, is measured using the formula
Physics Instructor’s Solution Manual
,1 | What Is Physics? 6
,
where v is velocity, d is the distance traveled, and t is the time the object took to travel the
distance.
If the velocity-time data are plotted on a graph, which variable will be on which
axis? Why?
A Time would be on the x-axis and velocity on the y-axis, because time is an
independent variable and velocity is a dependent variable.
B Velocity would be on the x-axis and time on the y-axis, because time is the
independent variable and velocity is the dependent variable.
C Time would be on the x-axis and velocity on the y-axis, because time is a dependent
variable and velocity is an independent variable.
D Velocity would be on the x-axis and time on the y-axis, because time is a dependent
variable and velocity is an independent variable.
Solution The correct answer is (A). Time would be on the x-axis and distance would be on the
y-axis, because time passes independently of how far the car travels. Therefore, time
is the independent variable while distance is the dependent variable.
17 A good-quality measuring tape can be off by 0.50 cm over a distance of 20 m. What is its
percent uncertainty in scientific notation?
A
B
C
D
Solution The correct answer is (A).
18 What is the definition of uncertainty?
A Uncertainty is the number of assumptions made prior to the measurement of a
physical quantity.
B Uncertainty is a measure of error in a measurement due to the use of a noncalibrated
instrument.
C Uncertainty is a measure of deviation of the measured value from the standard value.
D Uncertainty is a measure of error in measurement due to external factors like air
friction and temperature.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 7
Solution The correct answer is (C). Uncertainty is a quantitative measure of how much your
measured values deviate from a standard or expected value.
Physics Instructor’s Solution Manual
,1 | What Is Physics? 8
Critical Thinking Items
1.1 Physics: Definitions and Applications
19 In what sense does Einstein’s theory of relativity illustrate that physics describes
fundamental aspects of our universe?
A It describes how speed affects different observers’ measurements of time and space.
B It describes how different parts of the universe are far apart and do not affect each
other.
C It describes how people think of other people’s views from their own frame of
reference.
D It describes how a frame of reference is necessary to describe position or motion.
Solution The correct answer is (A). According to Einstein's theory of relativity, gravity or the
speed of the observer can affect what they observe as measured time intervals and
measured distances, as occurs with length contraction or time dilation.
20 Yes or no—Can classical physics be used to accurately describe a satellite moving at a
speed of ? Explain why or why not.
A No, because the satellite is moving at a speed much slower than the speed of the light
and is not in a strong gravitational field
B No, because the satellite is moving at a speed much slower than the speed of the light
and is in a strong gravitational field
C Yes, because the satellite is moving at a speed much slower than the speed of the light
and it is not in a strong gravitational field
D Yes, because the satellite is moving at a speed much slower than the speed of the light
and is in a strong gravitational field
Solution The correct answer is (C). Yes, classical physics could describe the motion of a
satellite, because it is moving at a speed much slower than the speed of light,
because it is not in a strong gravitational field, and because it involves an object that
is visible to the naked eye.
21 What would be some ways in which physics was involved in building the features of the
room you are in right now?
A Physics is involved in the structural strength and dimensions of the room.
B Physics is involved in the air composition inside the room.
C Physics is involved in the desk arrangement inside the room.
D Physics is involved in the behavior of living beings inside the room.
Solution The correct answer is (A). The physics of gravity, weight, and forces was used to
design the walls, ceilings, and floors in the room so they could hold up people and
Physics Instructor’s Solution Manual
, 1 | What Is Physics? 9
furniture. Knowledge of physics involving electricity went into developing lighting,
fans, electrical outlets, and other electrical devices in the room.
22 What theory of modern physics describes the interrelationships between space, time,
speed, and gravity?
A Atomic theory
B Nuclear physics
C Quantum mechanics
D General relativity
Solution The correct answer is (D). Einstein came up with general relativity to explain how
gravity is a result of bending of space and time.
23 According to Einstein’s theory of relativity, how could you effectively travel many years
into Earth’s future, but not age very much yourself?
A By traveling at a speed equal to the speed of light
B By traveling at a speed faster than the speed of light
C By traveling at a speed much slower than the speed of light
D By traveling at a speed slightly slower than the speed of light
Solution The correct answer is (D). You could do this by traveling away from Earth at near the
speed of light, because measured time intervals are shorter in the frame of
reference of the spaceship, in which you are at rest, than measured from Earth,
where you are seen as moving.
1.2 The Scientific Methods
24 You notice that the water level flowing in a stream near your house increases when it
rains and the water turns brown. Which hypothesis best explains why the water turns
brown? Assume you have all of the means to test the contents of the stream water.
A The water in the stream turns brown because molecular forces between water
molecules are stronger than mud molecules.
B The water in the stream turns brown because of the breakage of a weak chemical
bond with the hydrogen atom in the water molecule.
C The water in the stream turns brown because it picks up dirt from the bank as the
water level increases when it rains.
D The water in the stream turns brown because the density of the water increases with
increase in water level.
Solution The correct answer is (C). The brown color of water comes from the dirt that is
picked up from the edges of the banks of the water.
Physics Instructor’s Solution Manual
