Table of Contents

1
Table of Contents
Chapter 9 Motion and Energy

• Chapter Preview
• 9.1 Describing Motion
• 9.2 Speed and Velocity
• 9.3 Acceleration
• 9.4 Energy

2
Chapter Preview Questions
Chapter 9 Motion and Energy

• 1. Is a moving bus a good reference point from
  which to measure your position?
• a. No, because it is often late.
• b. No, because it is not a stationary
  object.
• c. Yes, because it is very large.
• d. Yes, because it can travel very far.

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Chapter Preview Questions
Chapter 9 Motion and Energy

• 1. Is a moving bus a good reference point from
  which to measure your position?
• a. No, because it is often late.
• b. No, because it is not a stationary
  object.
• c. Yes, because it is very large.
• d. Yes, because it can travel very far.

4
Chapter Preview Questions
Chapter 9 Motion and Energy

• 2. To describe a friends position with respect
  to you, you need to know
• a. Your friends distance from you.
• b. The direction your friend is facing.
• c. Your friends distance and direction
  from you.
• d. Your friends distance from a nearby
  object.

5
Chapter Preview Questions
Chapter 9 Motion and Energy

• 2. To describe a friends position with respect
  to you, you need to know
• a. Your friends distance from you.
• b. The direction your friend is facing.
• c. Your friends distance and direction
  from you.
• d. Your friends distance from a nearby
  object.

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Chapter Preview Questions
Chapter 9 Motion and Energy

• 3. Two cars traveling in the same direction pass
  you at exactly the same time. The car that is
  going faster
• a. moves farther in the same amount of
  time.
• b. has more mass.
• c. has the louder engine.
• d. has less momentum.

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Chapter Preview Questions
Chapter 9 Motion and Energy

• 3. Two cars traveling in the same direction pass
  you at exactly the same time. The car that is
  going faster
• a. moves farther in the same amount of
  time.
• b. has more mass.
• c. has the louder engine.
• d. has less momentum.

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Chapter Preview Questions
Chapter 9 Motion and Energy

• 4. To describe an objects motion, you need to
  know its
• a. position.
• b. change in position.
• c. distance.
• d. change in position over time.

9
Chapter Preview Questions
Chapter 9 Motion and Energy

• 4. To describe an objects motion, you need to
  know its
• a. position.
• b. change in position.
• c. distance.
• d. change in position over time.

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Chapter 9 Motion and Energy
How can you describe an objects motion?

• You are in a stationary car and another car
  passes you. How would you describe the motion of
  the other car?

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Chapter 9 Motion and Energy
Use Related Words
Word Definition Example Sentence

After investigating the evidence, they concluded
that everyone should wear a bicycle helmet.
conclude
v. to decide by reasoning
12
Chapter 9 Motion and Energy
Use Related Words
Word Definition Example Sentence

n. a series of numbers and symbols that
represents a mathematical rule
formula
The formula for the area of a circle is A pr2.
13
Chapter 9 Motion and Energy
Use Related Words
Word Definition Example Sentence

adj. the possibility that something will
develop in a certain way
The student who is studying chemistry is a
potential chemist.
potential
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Chapter 9 Motion and Energy

• Apply It!
• Choose the word from the table that best
  completes the sentence.
• The for finding the area of a
  rectangle is A l x w.
• formula
• 2. After waiting for 20 minutes, he
  that his friend was not coming.
• concluded
• 3. The heavy rains and rising river are a
  problem for people
• who live beside the river.
• potential

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End of Chapter Preview
Chapter 9 Motion and Energy
16
Section 1Describing Motion
Chapter 9 Motion and Energy

• When is an object in motion?
• What is the difference between distance and
  displacement?

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Relative Motion
Chapter 9 Motion and Energy - Describing Motion

• Whether or not an object is in motion depends on
  the reference point you choose.

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Distance and Displacement
Chapter 9 Motion and Energy

• Distance is the total length of the actual path
  between two points. Displacement is the length
  and direction of a straight line between starting
  and ending points.

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End of SectionDescribing Motion
Chapter 9 Motion and Energy
20
Section 2Speed and Velocity
Chapter 9 Motion and Energy

• When is an object in motion?
• What is the difference between distance and
  displacement?

21
Calculating Speed

Chapter 9 Motion and Energy

• If you know the distance an object travels in a
  certain amount of time, you can calculate the
  speed of the object.

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Graphing Motion
Chapter 9 Motion and Energy

• You can use distance-versus-time graphs to
  interpret motion.

23
Graphing Motion Activity
Chapter 9 Motion and Energy

• Click the Active Art button to open a browser
  window and access Active Art about graphing
  motion.

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Velocity
Chapter 9 Motion and Energy

• Click the Video button to watch a movie about
  velocity.

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End of SectionSpeed and Velocity
Chapter 9 Motion and Energy
26
Section 3Acceleration
Chapter 9 Motion and Energy

• What kind of motion does acceleration refer to?
• How do you calculate acceleration?
• What graphs can be used to analyze the motion of
  an accelerating object?

27
Calculating Acceleration
Chapter 9 Motion and Energy

• To determine the acceleration of an object, you
  must calculate its change in velocity per unit of
  time.

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Calculating Acceleration
Chapter 9 Motion and Energy

• As a roller-coaster car starts down a slope, its
  velocity is 4 m/s. But 3 seconds later, its
  velocity is 22 m/s in the same direction. What is
  its acceleration?
• Read and Understand
• What information have you been given?
• Initial velocity 4 m/s
• Final velocity 22 m/s
• Time 3 s

29
Calculating Acceleration
Chapter 9 Motion and Energy

• As a roller-coaster car starts down a slope, its
  velocity is 4 m/s. But 3 seconds later, its
  velocity is 22 m/s in the same direction. What is
  its acceleration?
• Plan and Solve
• What quantity are you trying to calculate?
• The acceleration of the roller-coaster car __
• What formula contains the given quantities and
  the unknown quantity?
• Acceleration (Final velocity - Initial
  velocity)/Time
• Perform the calculation.
• Acceleration (22 m/s - 4 m/s)/3 s 18 m/s/3 s
• Acceleration 6 m/s2
• The acceleration is 6 m/s2 down the slope .

30
Calculating Acceleration
Chapter 9 Motion and Energy

• As a roller-coaster car starts down a slope, its
  velocity is 4 m/s. But 3 seconds later, its
  velocity is 22 m/s in the same direction. What is
  its acceleration?
• Look Back and Check
• Does your answer make sense?
• The answer is reasonable. If the cars velocity
  increases by 6 m/s each second, its velocity will
  be 10 m/s after 1 second, 16 m/s after 2 seconds,
  and 22 m/s after 3 seconds.

31
Calculating Acceleration
Chapter 9 Motion and Energy

• Practice Problem
• A falling raindrop accelerates from 10 m/s to 30
  m/s in 2 seconds. What is the raindrops
  acceleration?

• (30 m/s - 10 m/s) 2 seconds 10 m/s2

32
Calculating Acceleration
Chapter 9 Motion and Energy

• Practice Problem
• A certain car can accelerate from rest to 27 m/s
  in 9 seconds. Find the cars acceleration.

• (27 m/s - 0 m/s) 9 s 27 m/s 9 s 3 m/s2

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Graphing Acceleration
Chapter 9 Motion and Energy

• You can use both a speed-versus-time graph and a
  distance-versus-time graph to analyze the motion
  of an accelerating object.

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Links on Acceleration
Chapter 9 Motion and Energy

• Click the SciLinks button for links on
  acceleration.

35
End of SectionAcceleration
Chapter 9 Motion and Energy
36
Section 4Energy
Chapter 9 Motion and Energy

• What factors affect an objects kinetic energy
  and potential energy?
• How can kinetic energy and potential energy be
  transformed?
• What is the law of conservation of energy?

37
Exponents
Chapter 9 Motion and Energy

• An exponent tells how many times a number is used
  as a factor. For example, 3 x 3 can be written as
  32. You read this number as three squared. In
  the formula for kinetic energy, speed is squared.
  For example, you can calculate the kinetic
  energy of a 70-kg person moving at a speed of 2
  m/s by using the formula below.
• KE ½ x Mass x Speed2
• ½ x 70 kg x (2 m/s) 2
• 140 kgm2/s2 or 140 joules.
• Note
• 1 kgm2/s2 1 joule

38
Exponents
Chapter 9 Motion and Energy

• Practice Problem
• What is the kinetic energy of a 30-kg rock moving
  at a speed of 10 m/s?

• 1,500 joules

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Kinetic Energy
Chapter 9 Motion and Energy

• Kinetic energy increases as mass and speed
  increase.

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Potential Energy
Chapter 9 Motion and Energy

• Gravitational potential energy increases as
  weight and height increase.

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Transformations BetweenPotential and Kinetic
Energy
Chapter 9 Motion and Energy

• A pendulum continuously transforms energy from
  kinetic to potential energy and back.

42
Energy Transformations Activity
Chapter 9 Motion and Energy

• Click the Active Art button to open a browser
  window and access Active Art about energy
  transformations.

43
Links on Energy
Chapter 9 Motion and Energy

• Click the SciLinks button for links on energy.

44
Links on Forms of Energy
Chapter 9 Motion and Energy

• Click the SciLinks button for links on forms of
  energy.

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End of SectionEnergy
Chapter 9 Motion and Energy
46
QuickTake Quiz
Chapter 9 Motion and Energy

• Click to start quiz.