acceleration - miss kelly's...

Acceleration

What did you notice about the

velocity of the marble as it went

down the ramp?

What do we call a change in

velocity?

What is “Acceleration”?

• A: The rate at which velocity changes!

– In other words: How fast something speeds

up, slows down, or even changes direction.

Speeding up: Slowing down: Changing direction:

You probably think it simply means to “speed up.” Well yes, and a bit more:

Acceleration = A change in Velocity

][

][2s

m

Time

VelocityonAccelerati

You already learned the

Velocity equation:

Here is the equation for Acceleration:

][

][

s

m

Time

cetanDisVelocity

Means “change”

Shortcut to help you remember

• V = A x T

• A = V/T

• T=V/ATA

V

Question

• What would the graph look like for a car

accelerating onto the highway?

Question

• What would the graph look like for a car

slowing down to a stop?

Review Constant Velocity

1 2 3 4 5

If you recall – a characteristic of

constant velocity is that all distances

between seconds are the same.

Time [Sec]

Dis

tance [

m]

1s slow

1.2m

2s slow

2.4m

3s slow

3.6m

0

1 2

3

4 5 6

Acceleration

With Acceleration, Notice the difference

of distance with the red acceleration lines

between each second?

1sec

1.0m

2sec

3m

1 2

Question

• What kind of graph will a negative

acceleration produce?

Time

Interpreting Acceleration on a

Graph

5 m

15 m

10 m

15 s10 s5 s

Dis

tance

Dis

tan

ce

Positive

Acceleration

Negative

Acceleration

Constant

Velocity

Question

• What kind of graph will a positive

acceleration produce in the negative

direction?

Time

Interpreting Acceleration on a

Graph

5 m

15 m

10 m

15 s10 s5 s

Dis

tance

Dis

tan

ce

Positive

Acceleration in a

negative direction

Negative

Acceleration in a

Positive direction

Flat line = No

velocity from the

POR

Time

Interpreting Acceleration on a

Graph

5 m

15 m

10 m

15 s10 s5 s

Dis

tance

This is the line of an object

with an “constant velocity”

Compare it to the line of

an object with a changing

Velocity = Acceleration!

It is also possible to have an

object with a negative acceleration

We can call this “Deceleration”

Notice the

downward curveIt is a nice straight line!

Straight lines on a graph mean “constant”

Curved lines mean a change

has occurred = Acceleration!Dis

tan

ce

Acceleration Formula for Distance2

2

1atD

][

][2s

m

Time

VelocityonAccelerati

Time Dist. Vel. Acc.

1

2

3

4

5