1. Unit 4 Motion & Forces

2. 2. Speed, Velocity, & Acceleration

3. You know a car is in motion if you see it in one place
then in another place in relation to an object

4. 3 ways to change motion
Speed
Velocity
Acceleration

5. The distance something moves in a certain time
Vocabulary:
speed
The distance something moves in a certain time
Distance
Speed =
Time

6. Many people can walk 2 miles in 1 hour
Speed =
1 hour
Their speed is 2 miles per hour
It is often written miles / hour

7. Some people can run 7 miles an hour or 7 miles / hour
The speed of 7 miles / hour is faster than 2 miles / hour

8. Speed in a certain direction
Vocabulary:
velocity
Speed in a certain direction

9. If you are running at 7 miles / hour along a straight path
your velocity is the same as your speed

10. But if you are running around a track you are changing direction
Your speed is the same, but your velocity is changing

11. Velocity changes when the direction of the motion changes

12. Vocabulary:
acceleration
a change in velocity

13. If you pedal a bicycle so that it speeds up
that is positive acceleration

14. If you use the brakes to slow down
that is negative acceleration