1. Acceleration

2. The rate of change in velocity

3. Acceleration The rate of change in velocity Examples…. –Speeding up Positive acceleration –Slowing down Negative acceleration Deceleration –Changing direction Centripetal acceleration

4. Acceleration Compare to speed Acceleration is the rate of change in either speed or direction, while speed is the rate of change in position. They are both rates, but they are rates of different things.

5. Acceleration Formula for calculating acceleration:

6. Acceleration Formula for calculating acceleration: V f = final velocity V s = starting velocity t= time a = acceleration

7. Acceleration One last way to write that formula: Which is read delta v over t or change in velocity over time.

8. Acceleration: Example What is the average acceleration of a subway train that speeds up from 6 m/s to 12 m/s in 2s?

9. Acceleration: Example What is the average acceleration of a subway train that speeds up from 6 m/s to 12 m/s in 2s? V f = 12 m/sa = ? V s = 6 m/s t= 2 s

10. Acceleration Problems What is the average acceleration of a subway train that speeds up from 6 m/s to 12 m/s in 2s? v f = 12 m/s v s = 6 m/s t = 2s

11. Acceleration Problems A person is traveling at 20 m/s in a car when the car hits a tree. The person comes to a complete stop in 0.4 seconds. What was the person’s acceleration?

12. Acceleration Problems A person is traveling at 20 m/s in a car when the car hits a tree. The person comes to a complete stop in 0.4 seconds. What was the person’s acceleration? v s = 20 m/s v f = 0 m/s t = 0.4s

13. Acceleration Problems A person is traveling at 20 m/s in a car when the car hits a tree. The person comes to a complete stop in 0.4 seconds. What was the person’s acceleration? v s = 20 m/s v f = 0 m/s t = 0.4s

14. Recognizing acceleration on a graph This graph shows positive acceleration because the object is getting faster. The distance traveled in each second is increasing. The graph is becoming more steep.

15. Recognizing acceleration on a graph This graph shows negative acceleration because the object is getting slower. The distance traveled each second is decreasing. The graph is getting less steep. Distance (m) Time (s)