Acceleration
What is acceleration?
Rate at which velocity changes
 Acceleration is a vector. It describes
changes in speed and direction.
 Can be an increase in speed or a
decrease in speed
 A decrease in speed is known as
deceleration.


Units for acceleration are m/s2

Objects falling near earth’s surface
accelerate downward at a rate of 9.8 m/s2
Constant acceleration

A steady change in velocity; the velocity
changes by the same amount each
second
Formula

Acceleration = change in velocity
total time
A = vf-vi
t

Where vf=final velocity, vi=initial velocity
Practice Problem #1

A ball rolls down a ramp, starting from rest.
After 2 seconds, its velocity is 6 m/s. What
is the acceleration of the ball?
Practice Problem #2

A car traveling at 10 m/s starts to
decelerate steadily. It comes to a stop in
20 seconds. What is its acceleration?
Problem #3

A child drops a ball from a bridge. The ball
strikes the water under the bridge 2
seconds later. What is the velocity of the
ball when it strikes the water?