1. Acceleration

2. Definition Acceleration: rate at which velocity changes
Remember: velocity is speed AND direction
THREE ways that something can have acceleration:
Increasing speed
Decreasing speed
Change in direction

3. Increasing Speed A softball accelerates when a pitcher throws it
A car accelerates to pass another car on the highway
You accelerate when you ride your bike down a hill

4. Decreasing Speed AKA: “negative acceleration”
A softball decelerates when it lands in a glove
A car decelerates when it stops at a red light

5. Change in Direction
If an object is at a constant speed, but changing direction, it is accelerating
A Ferris Wheel accelerates because it’s changing direction, but at a constant speed
A car changes direction when rounding a curve.

6. Calculating Acceleration
Acceleration = Final velocity – Initial velocity
The SI unit of acceleration is m/s2
Time

7. Sample Problem
As a roller coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration?
Initial Velocity: Vi
Final Velocity: Vf
Time:

8. Graphing Acceleration
Speed vs. Time Graph