Do Now!Can you put the “Unit 1

CONTENTS” sheet in the front of your

folders.

There will be a Unit 1 TEST on

Friday 25th September, when

Mr Porter will also collect in your

folders.

A reminder

No movement

distance

time

speed

time

Constant speed

distance

time

speed

time

Area = distance travelled

Constant acceleration

distance

time

speed

time

Area = distance travelled

Gradient = acceleration

a = (v-u)/t

Today’s lesson

• Define displacement, velocity, speed and acceleration

• Explain the difference between instantaneous and average values of speed, velocity and acceleration

Displacement

Displacement

• Displacement the distance moved in a stated direction (the distance and direction from the starting point). A VECTOR

Velocity?

Velocity?

• Velocity is the rate of change of displacement. Also a VECTOR

An interesting example

Think of a dog (dead) orbiting the earth with constant speed (in a circle).

An interesting example

At this point, what is its velocity?

velocity?

An interesting example

velocity

An interesting example

velocity?

What is its velocity here?

An interesting example

velocity

As you can see the velocity has changed as it is now going in another direction.

An interesting example

velocity

We have constant speed but changing velocity.

Acceleration?

Acceleration?

• Acceleration is the rate of change of velocity. Also a VECTOR

An interesting example

velocity

We have constant speed but changing velocity.

Of course a changing velocity means it must be accelerating!

Average speed/velocity?

Average speed/velocity?

• Average speed/velocity is change in distance/displacement divided by time taken over a period of time.

Instantaneous speed/velocity?

Instantaneous speed/velocity?

• Instantaneous speed/velocity is the change in distance/displacement divided by time at one particular time.

Let’s try some questions!

Page 45 questions 1, 2, 3, 4, 5, 8, 10.