1. Speeding Up and Slowing Down
Acceleration and Deceleration

2. ACCELERATION Change in VELOCITY occurring over TIME
Units: METERS PER SECOND2
VECTOR
Negative Velocity
Negative Velocity
Positive Velocity
Positive Velocity
Negative Acceleration
Negative Acceleration
Positive Acceleration
Positive Acceleration
Slowing down
Eventually speeds up in + direction!
Slowing down
Eventually speeds up in – direction!
Speeding up in + direction
Speeding up in - direction

3. Equations An object’s velocity at any point in time can
be found by considering:
- its starting velocity
its acceleration
the amount of time over
which it accelerates
Acceleration is the rate
of change in velocity over time
Subscript f = “final”
Subscript i = “initial”

4. Tips on Solving Problems
In order to receive full credit on tests and quizzes, including the Regents Test, you have to include the following in your answer:
The equation you will use
The given values WITH UNITS
The correct answer WITH UNITS
*99% of the time, if there is a number it HAS UNITS
** Units for a certain number have to appear at least ONCE in your solution

5. 2 Methods
A car travels 100 meters in 20 seconds, calculate its velocity.
Recommended Method
Alternative Method

6. Example
Two cars start at the same point. Car A starts with a velocity of -5 meters per second while Car B starts with a velocity of +3 meters per second. At the end of 15 seconds, Car A has a velocity of +25 meters per second.
Calculate Car A’s acceleration

7. Example
Two cars start at the same point. Car A starts with a velocity of -5 meters per second while Car B starts with a velocity of +3 meters per second. At the end of 15 seconds, Car A has a velocity of +25 meters per second.
If Car B has the same acceleration, determine its speed at 15 seconds

8. SUMMARY Acceleration Describe the 2 methods to solve problems
Definition?
Vector or Scalar?
Units?
Equations?
Describe the 2 methods to solve problems