Matter in Motion

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• Matter in Motion

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Measuring Motion

• MOTION - A change in position over time.
• Motion is observed by using a reference point.
• REFERENCE POINT - The object that appears to stay
  in place.

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What is the reference point?

• How do we know that Bart and Homer are in motion?

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What is speed?

• SPEED - The rate at which an object moves.
• Speed depends on DISTANCE and TIME.

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Average Speed

• Most of the time an object does not travel at a
  constant speed.
• You do not walk to class at the same speed.
• The car or bus that brought you to school did not
  travel at a constant speed.

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• Average speed is calculated using the following
  equation
• Average speed total distance
• total time

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Calculate the average speed

• This man drives 2 hours each way to his Hair
  Club for Men appointment. He travels a total
• distance of 240
• miles. Figure his
• average speed.

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VELOCITY

• Velocity is speed with a direction.
• An example of velocity is
• 50 meters per second SOUTH
• Directions can include north, south, east, west,
  forward, backward, left, right, up and down

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Look at the difference!

• 50 m/s is speed
• 50 m/s forward is velocity
• 24 mph is speed
• 24 mph west is velocity

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ACCELERATION

• Acceleration is a change in DIRECTION or SPEED
  over time.
• A car turning a corner is accelerating because it
  changes direction.
• A runner taking off in a race is accelerating
  because his speed is increasing.

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• This train is accelerating because it is
  constantly changing direction.

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Formula for Acceleration

• Acceleration
• final velocity - original velocity
• time

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• Negative acceleration is called deceleration.
  When an object slows down it still changes speed.
  It is still accelerating!

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Lets Practice Acceleration

• Gizmo the guinea pig rides a bicycle to school
  daily. She reaches a speed of 12 miles per hour
  in 4 seconds. What is Gizmos rate of
  acceleration?

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What does it mean?

• Gizmos final velocity was 12 mph. Her original
  velocity was 0 mph. 12 - 0 equals 12. Divide 12
  by the amount of time it took her (4 seconds),
  and Gizmos rate of acceleration is 3 m/h/s.
• This means Gizmos speed accelerated 3 mph every
  second.

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What is Gizmos speed each second during the
previous problem?
Gizmos Speed
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Lets see what you know!

• Answers the following questions.

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Figure the average speed?

• The roller coaster travels a distance of 360
  feet in 3 minutes. Figure its average speed per
  minute.
• Figure its average speed per second.

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Is this acceleration?

• Is this car accelerating? Why or why not?

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Figure the acceleration

• The bikers are traveling south at a speed of 35
  miles per hour. They have to adjust their speed
  to 20 miles per hour to make a curve. It took
  them 3 seconds. Figure the acceleration.

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Create a chart
Bikers speed

• Create a chart showing the speed of the bikers at
  each of the 3 seconds.

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Calculate the speed and figure the problem

• Peppy the Penguin can ice skate very well. He can
  complete a 1/2 mile lap in 3 minutes. How long
  will it take Peppy to ice skate 12 miles?

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Youve just finished Professor Know-It-Alls Quiz

• How did you do?