Circular Motion What forces are involved when objects

Circular Motion 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.

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

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

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

• 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

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.

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. • Can you feel the difference? ! • What has changed?

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.

Have a go at the questions

The bucket of water trick