Centripetal Force

An accelerating object can be undergoing a change in direction without the speed of the object changing.

That a centripetal force is a force acting towards the centre of a circle.

Key: state that a force required for an object to move in a circle is a centripetal force

Stretch: draw a diagram showing the force necessary to make an object undergo circular motion

Challenge: Identify the forces that provide the centripetal force on an object in an given situation

That the size of a centripetal force depends on the radius of the circular path, the speed of rotation and the mass of an object?

Is this true or false?

Centripetal force

Centri = Centre

It is a force that makes a body follow a curved path, and towards the centre.

Watch this.....

Now draw a force diagram explaining the forces that are acting on the person.

Does the distance from the centre of the rotating disc have an effect on the size of the forces?

For a moving object at a constant speed

its velocity is directed along a tangent to the circle of direction

the velocity constantly changes direction as it moves around the circle

the change of velocity is towards the centre of the circle

Therefore, the object is constantly accelerating towards the centre of the circle.

So the force on the object act towards the centre of the circle.

This force that acts towards is a resultant force, called the centripetal force, because it always acts towards the centre of the circle.

The mass of the body increases The speed of the body increases The radius of the circle increases

The direction of the centripetal forces is always towards the centre of the circle.

IF you remove the centripetal force then it will go off at an tangent.

In each of these situations a single force acts as the centripetal force.

Match each situation to the words:

Electrostatic force, friction, gravity, pull (tension)

1. A car travelling around a bend. 2. A stone being whirled round on the end

of a string. 3. A planet moving round the sun. 4. An electron orbiting the nucleus of an

atom.

1. A car travelling round a bend = FRICTION 2. A stone being whirled round on the end

of the string = PULL 3. A planet moving around the sun =

GRAVITY 4. An electron orbiting the nucleus of an

atom = ELECTROSTATIC FORCES

The centripetal force of an aircraft is the resultant force of the two other forces acting on the aircraft: the weight of the aircraft and the lift of the aircraft