acceleration - miss kelly's...
TRANSCRIPT
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