1. What forces are involved when objects move in a circular motion?
Starter
Sketch a diagram of the roundabout and draw on the forces that act on a car.

2. Glossary
Centripetal force – the resultant force towards the centre of a circle acting on an object moving in a circular path.

3. Watch these clips – write down anything of interest
Fair ground ride
G force training
Why do these objects move in a circle?

4. Demo – spinning object
Spin an object, let go , moves in a tangential way.

5. The object is accelerating towards the centre of the circle.
An object moving in a circular motion at a constant speed, will have a constantly changing velocity. The change of velocity is towards the centre.
The object is accelerating towards the centre of the circle.
The velocity is directed along a tangent to the circle.
Note: Accn = change in velocity / time

6. Acceleration Accn = the change in velocity / time
Therefore – acceleration is continually increasing towards the centre of the circle.
BE CAREFUL! The acceleration changes the direction not the speed.

7. Task: Centripetal Force
Swing a small bung on a string around your head then try a big bung.
Can you feel the difference?!
What has increased?
NOW – try 1 size of bung with a short piece of string then a long piece.
What has changed?

8. Factors affecting centripetal force
Radius of circle
Mass of object
Speed of rotation
A greater mass gives a greater centripetal force.
Decrease the radius and increase the centripetal force.

9. Have a go at the questions

10. The bucket of water trick