ACCELERATION
Motion is change of position
Motion is described by velocity:
How fast? Which way?
Changing motion means:
Speeding up,
Slowing down,
Changing direction (turning)
ACCELERATION
• A car is accelerating whenever there is a change
in velocity
• Acceleration also applies to changes in direction.
•It is important to distinguish
between speed and velocity.
Acceleration is defined as
the rate of change in
velocity, rather than speed
ACCELERATION
Acceleration is the rate at which velocity changes:
Acceleration is how fast how fast changes
or how fast the direction changes
Falling upward:
constant acceleration
Now consider a ball thrown straight up at 30 m/s:
What happens on the way up?
How fast is the ball moving 1 s, 2 s, 3 s later?
Where is the ball when v = 0?
How long does the ball take to reach the
highest point?
How fast is the ball moving 4 s later?
How long does the ball take to reach the
person?
How fast is the ball moving when it reaches
the person?
Ball Toss Experiment
Ball is in your
hands
Ball is in your
hands
Ball is in your
hands
Ball is in your
hands
Ball Toss Experiment
Ball is in
the air
Ball is in
the air
Ball is in your
hands
Ball is in your
hands
Motion with Constant Acceleration
- 4.8 X 2 = 9.6
equal
equal
Motion with Constant Acceleration
General equations:
y = ½ at2 + vot
v = at + vo
a is constant ( a
number)
Free Fall: Constant Acceleration
The acceleration of an object in free
fall is about 10 meters per second
every second
Or 10 m/s/s
The rock is falling faster and faster:
Each second its velocity increases by
10 m/s
Fill out the table:
Time,
seconds
0
1
2
3
4
Velocity,
m/s
0
10
20
30
40
t
10t
Graph these values: make a velocity-time graph
Motion with Constant Acceleration
Velocity-Time Graph
On a velocity-versus-time graph,
acceleration = slope
Free Fall: Constant Acceleration
The acceleration of an object in free
fall is about 10 meters per second
every second
Or 10 m/s/s
The rock is falling faster and faster:
Each second its velocity increases by
10 m/s
Time,
seconds
0
1
2
3
4
Velocity,
m/s
0
10
20
30
40
t
10t
Motion with Constant Acceleration
Position-Time Graph
y = ½ at2
Position, Velocity, and Acceleration
Motion Graphs
Constant Acceleration Graphs
Race Cars