Centrifugal force represents the effects of inertia when a body is moving about a central point and which is experienced as an outward force away from the centre of rotation. It is distinct from the centripetal force which is the force towards the central point which keeps the body moving about the central point. It arises because of the inertia of a body – the reluctance of a body to change either speed or direction, which together constitute it's velocity. With no net external force acting, a body will continue to move in a straight line. If a force is applied to make the body move in a circle, for example, a force directed towards a central point must be applied.

The force may be a tension in a string, gravitational, the force between electrically charged particles, a reaction force or have another origin. The magnitude of this centripetal force iswhere

is the mass of the body performing circular motion

is it's speed

is the radius of the motion

The centrifugal force also has magnitudebut is directed outwards as shown above.