CHAPTER 2 REPRESENTING MOTION

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CHAPTER 2 REPRESENTING MOTION

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• In this chapter you will
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•  Represent motion through the use of words,
  motion diagrams, and graphs.
• Use the terms position, distance, displacement,
  and time interval in a scientific manner to
  describe motion.

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CHAPTER 2 SECTIONS

• Section 2.1 Picturing Motion
• Section 2.2 Where and When?
• Section 2.3 Position-Time Graphs
• Section 2.4 How Fast?

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SECTION 2.1 PICTURING MOTION

• Objectives
• Draw motion diagrams to describe motion.
• Develop a particle model to represent a moving
  object.

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INTRO/ALL KINDS OF MOTION

• Perceiving motion is instinctive your eyes pay
  more attention to moving objects than to
  stationary ones. Movement is all around you.
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• Movement travels in many directions, such as the
  straight-line path of a bowling ball in a lanes
  gutter, the curved path of a tether ball, the
  spiral of a falling kite, and the swirls of water
  circling a drain.
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• When an object is in motion, its position
  changes. Its position can change along the path
  of a straight line, a circle, an arc, or a
  back-and-forth vibration.
• When beginning a new area of study, it is
  generally a good idea to begin with what appears
  to be the least complicated situation, learn as
  much as possible about it, and then gradually add
  more complexity to that simple model.

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ALL KINDS OF MOTION

• A description of motion relates to Place and
  Time.
• You must be able to answer the questions of where
  and when an object is positioned to describe its
  motion.

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MOTION DIAGRAMS

• Motion Diagram a series of images showing the
  positions of a moving object taken at regular or
  equal time intervals.

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THE PARTICLE MODEL

• Particle Model is a simplified version of a
  motion diagram in which the object in motion is
  replaced by a series of single points.

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QUESTION 2

• A car is moving at a speed of 90 km/h. What is
  the speed of the car in m/s? (Hint Use
  Dimensional Analysis)
• 90 km 1 h 1000 m 25
  m/s
• h 3600 s 1 km

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QUESTION 1

• Explain how applying the particle model produces
  a simplified version of a motion diagram?
• Keeping track of the motion of the runner is
  easier if we disregard the movements of the arms
  and the legs, and instead concentrate on a single
  point at the center of the body. In effect, we
  can disregard the fact that the runner has some
  size and imagine that the runner is a very small
  object located precisely at that central point. A
  particle model is a simplified version of a
  motion diagram in which the object in motion is
  replaced by a series of single points.

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QUESTION 2

• Which statement describes best the motion diagram
  of an object in motion?
• A graph of the time data on a horizontal axis and
  the position on a vertical axis.
• A series of images showing the positions of a
  moving object at equal time intervals.
• Diagram in which the object in motion is replaced
  by a series of single point.
• A diagram that tells us the location of zero
  point of the object in motion and the direction
  in which the object is moving.
• B A series of images showing the positions of a
  moving object at equal time intervals is called a
  motion diagram.

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QUESTION 3

• What is the purpose of drawing a motion diagram
  or a particle model?
• To calculate the speed of the object in motion.
• To calculate the distance covered by the object
  in a particular time.
• To check whether an object is in motion.
• To calculate the instantaneous velocity of the
  object in motion.
• C To check whether an object is in motion.