1. Objective
SWBAT use velocity-time graphs to determine an object’s acceleration.

2. Review
acceleration: a change in an object’s speed (speeding up OR slowing down)

3. Speed-Time (Velocity-Time) Graph

4. Interpreting Distance-Time Graphs
From point A (t = 0 s) to point B (t = 2 s)
sf = 10 m/s
si = 0 m/s
t = 2 s – 0 s = 2 s
 Speed is increasing by 5 m/s every second.

5. Interpreting Distance-Time Graphs
From point B (t = 2 s) to point C (t = 4 s)
sf = 10 m/s
si = 10 m/s
t = 4 s – 2 s = 2 s
 Object is moving forward at a constant speed of 10 m/s. It is not getting faster or slower.

6. Interpreting Distance-Time Graphs
From point C (t = 4 s) to point D (t = 6 s)
sf = 4 m/s
si = 10 m/s
t = 6 s – 4 s = 2 s
 Speed is decreasing by 3 m/s every second.

7. During what time periods is the person accelerating
During what time periods is the person accelerating? From 0 s to 2 s AND from 4 s to 6 s (slowing down)
During what time periods is the person moving at a constant speed? From 2 s to 4 s

8. What is the acceleration from t = 0 s to t = 3 s?

9. During what time intervals is the speed changing?
During what time intervals is the speed constant?