1. Acceleration

2. Acceleration
Acceleration – The change in the rate of speed (velocity) over time.
a = Δv = vf – vi
t t

3. What are 3 ways an object can accelerate?
Speed up
Slow down
Change direction
Remember… Velocity is speed with direction!!

4. Calculating Acceleration
To find acceleration you need four things:
a = acceleration
vf = final speed
vi = initial speed
t = time
a = vf – vi t
Solving for acceleration is a 5-step process just like velocity.

5. Let’s try to solve an acceleration problem:
A truck increased its speed from 20 m/s to 50 m/s in 2s. What was the rate of acceleration for the truck?
Step 1: List the givens and unknown
Step 2: Write the equation
a = vf – vi t
vf =
50 m/s
vi =
20 m/s
Step 3: Plug the number in place of the letters.
t =
2 s
a = m – 20m
s s 2s
a = ?
m/s2
Step 4 and 5: Solve the problem and write the unit

6. The unit for acceleration is meter per second squared or m/s2.
Here is why:
a = 50m – 20m
s s s
a = 30m = 15 m
s 2s s2
a = vf – vi t
The two second units in the denominator combine

7. Rearrangement of the equation to solve for final velocity

8. A graph of speed vs. time can also be used to calculate acceleration.
Slope = rise over run
2.45