Moving in a Circle (Also seen in GCSE Physics 3)

For an object to continue to move in a circle a force is needed that acts on the object towards the centre of the circle. This is called the centripetal force and is provided by a number of things:

For a satellite orbiting the Earth it is provided by gravitational attraction.

For a car driving around a roundabout it is provided by the friction between the wheels and the road.

For a ball on a string being swung in a circle it is provided by the tension in the string.

Centripetal force acts from the body to the centre of a circle

Since F=ma the object must accelerate in the same direction as the resultant force. The object is constantly changing its direction towards the centre of the circle.

Centripetal acceleration has direction from the body to the centre of the circle