Velocity and Acceleration

**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 s v is greater

b. Lamborghini’s 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=v f -v i

or ∆v

t 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/s 2

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 (v i ): 0 m/s

Final velocity (v(

f ): 60 m/s

Time: 6 seconds

A= 60m/s – 0 m/s

6 s

= 10 m/s 2

Homework:

Questions 1-31

3 on page 67.

Complete mini-lab

lab…

Does greater velocity require

greater acceleration?