Velocity and Acceleration
I’m the king
of the
world!!!!
Woo-hoo!!!
Velocity
Speed
only describes how fast
something is moving
Velocity describes both speed
AND direction!
Velocity
Concep question:
Picture two sports cars racing down the
highway. The Ferrari is traveling west
while the Lamborghini is traveling east.
They both have a speed of 100km/h.
What can you conclude about their
velocities?
a. Ferrari’s v is greater
b. Lamborghini’s v is greater
c. Their velocities are the same
d. Their velocities are different
Velocity
The
answer is d. Both cars have
the same speed, however the
direction in which they are
traveling is different. Their
velocities are different because
their directions are different.
Change in velocity
Speed
may not always be
constant.
The velocity of an object may
change, even if the speed
remains the same.
Acceleration
Acceleration
is the rate of
change of velocity
Velocity includes both speed and
direction, therefore acceleration
is both the rate of change in
velocity and direction of that
change.
Acceleration
If
acceleration is in the same
direction as the object, the
objects speeds up.
If acceleration is the opposite
direction as the object, the
object slows down.
Acceleration
Acceleration
also depends on
the time interval.
To calculate the acceleration of
an object, divide the change in
velocity by the time.
a=vf-vi
t
or ∆v
t
Acceleration Units
The unit for velocity is meters / second
m/s
The unit for time is seconds (s)
Therefore, the unit for acceleration is
meters/seconds = m/s2
seconds
“Meters per second squared”
Acceleration Sample Problem
A race car sits at the starting line at Atco
raceway. The light turns green and the
driver presses the pedal to the metal. The
velocity changes from 0 m/s to 60m/s
in 6 seconds. What is the acceleration of
the car?
Solution:
List the known information:
initial velocity (vi): 0 m/s
Final velocity (vf): 60 m/s
Time: 6 seconds
A= 60m/s – 0 m/s = 10 m/s2
6s
Homework:
Questions
1-3 on page 67.
Complete mini-lab…
Does greater velocity require
greater acceleration?