1. Change in Velocity Velocity rarely stays constant
Acceleration is the rate of change of velocity
When the velocity of an object changes, the object is accelerating
A change in velocity can be either a change in how fast something is moving, or a change in the direction it is moving
Acceleration occurs when an object changes its speed, its direction, or both
Acceleration- the rate at which velocity changes in time (speed OR direction components)

2. Change in Velocity In a car we can change our velocity 3 ways:
Speed up
Slow down
Change direction
All of these would be considered acceleration

3. Change in Velocity We say that this car is accelerating
because its velocity is increasing
because its direction is changing as it turns, which means its velocity is changingeven though its speed stays constant
We say that this car is accelerating because its velocity is decreasing. Decreasing velocity is still acceleration, although it is a negative
acceleration
30 km/h km/h
60 km/h
60 km/h
60 km/h km/h km/h

4. Change in Velocity
Changing speed changes velocity and is therefore considered acceleration
Positive acceleration speeding up
Negative acceleration slowing down

5. Acceleration Formula T
A = Vfinal–Vinitial OR

6. Example: A cars velocity changes from 0. 0m/s south to 50
Example: A cars velocity changes from 0.0m/s south to 50.0m/s south in 10.0 seconds. Calculate the cars acceleration
Vinitial:
0.0m/s south
Given:
Vfinal:
50.0m/s south
10.0 seconds
Time:
Uknown:
acceleration
A = Vfinal – Vinitial
Time
Equation:
Setup:
A = 50.0m/s – 0.0m/s
10.0s
A = 5.0 m/s/s or m/s2
Solve:

7. Check for Understanding A car traveling at 60 mph accelerates to
90 mph in 3 seconds. What is the
car’s acceleration?
Given:
Uknown:
Equation:
Setup:
Solve:

8. Check for Understanding A car traveling at 60 mph accelerates to
90 mph in 3 seconds. What is the
car’s acceleration?
Given:
Velocity(initial) =
60 mph
Velocity(final) =
90 mph
Time =
3 seconds
Unknown:
What is the car’s acceleration?
Equation:
Acceleration
= Velocity(final) - Velocity(initial)
time
Setup:
90 mph - 60 mph
3 seconds
30 mph
3 seconds = =
Solve: =
10 mph/second

9. Check for Understanding
A car traveling at 60 mph slams on the breaks to avoid hitting a deer. The car comes to a safe stop 6 seconds after applying the breaks. What is the
car’s acceleration?
Given:
Unknown:
Equation:
Setup:
Solve:

10. Check for Understanding
A car traveling at 60 mph slams on the breaks to avoid hitting a deer. The car comes to a safe stop 6 seconds after applying the breaks. What is the
car’s acceleration?
Given:
Velocity(initial) =
60 mph
Velocity(finall) =
0 mph
Time =
6 seconds
Unknown:
Acceleration
Acceleration
= Velocity(final) - Velocity(initial)
time
Equation:
0 mph - 60 mph
6 seconds
-60 mph
6 seconds
Setup: = =
Solve: =
-10 mph/second