Chapter 12: Motion and Momentum

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Chapter 12 Motion and Momentum

• Section 1 What is Motion?

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Matter and Motion

• All matter in the universe is constantly in
  motion, from the revolution of Earth around the
  Sun to elections moving around the nucleus of an
  atom.

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Changing Position

• The runners sprint from the start line to the
  finish line.
• Their positions change, so they are in motion.

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SPEED

• Speed is the distance traveled divided by the
  time taken to travel the distance

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AVERAGE SPEED

• Average speed is found by dividing the total
  distance traveled by the time taken.
• An object in motion can change speeds many times
  as it speeds up or slows down.

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• If it takes you 0.5 h to walk 2 km to the
  library, your average speed would be as follows

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Graphing Motion

• You can represent the motion of an object with a
  distance-time graph.
• For this type of graph, time is plotted on the
  horizontal axis, and distance is plotted on the
  vertical axis.

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Distance-Time Graphs and Speed

• Look at the graph.
• According to the graph, after 1 s student A
  traveled 1 m.

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VELOCITY

• The velocity of an object is the speed of the
  object and direction of its motion.
• 5 M/S DUE NORTH

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QUESTION 1

• To determine whether something has changed
  position, you need a _______.
• A. compass
• B. global positioning system
• C. map
• D. reference point

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• The answer is D. If someone starts a car and
  drives it 100 meters from its parking spot, the
  parking spot can be used as a point of reference
  to show that the car moved.

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Speed equals distance divided by _______.

• A. force
• B. mass
• C. time
• D. velocity

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Answer

• The answer is C. The smaller the t value in
  sd/t, the greater the speed.