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Speed, Velocity, & Acceleration

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You know a car is in motion if you see it in one place

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then in another place in relation to an object

3 ways to change motion

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1. Speed2. Velocity3. Acceleration

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Vocabulary:

speed

The distance something moves in a certain time

Speed = Distance Time

Many people can walk 2 miles in 1 hour

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Speed =2 miles1 hour

Their speed is 2 miles per hour

It is often written 2 miles / hour

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Some people can run 7 miles an hour

or7 miles / hour

The speed of 7 miles / hour is faster than 2 miles / hour

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Vocabulary:

velocity

Speed in a certain direction

If you are running at 7 miles / hour along a straight path

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your velocity is the same as your speed

But if you are running around a track you are changing

direction

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Your speed is the same, but your velocity is changing

Velocity changes when the direction of the motion

changes

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Vocabulary:

acceleration

a change in velocity

If you pedal a bicycle so that it speeds up

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that is positive acceleration

If you use the brakes to slow down

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that is negative acceleration