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. Do Now!

A reminder

No movement speed time distance time

Constant speed speed time distance time Area = distance travelled

Constant acceleration speed time Gradient = acceleration a = (v-u)/t distance time Area = distance travelled

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). 11

An interesting example At this point, what is its velocity? velocity? 12

An interesting example velocity 13

An interesting example What is its velocity here? velocity? 14

An interesting example As you can see the velocity has changed as it is now going in another direction. velocity 15

An interesting example We have constant speed but changing velocity. velocity 16

Acceleration?

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

An interesting example We have constant speed but changing velocity. Of course a changing velocity means it must be accelerating! velocity 19

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.