Moving in Circles
If something is going in a circle, its velocity is changing, even if its speed is constant. This is because it is changing direction. If the velocity is changing the object must be accelerating. We know from Newton's Laws that something will only accelerate when a force is being applied.
We call the force that keeps things moving in a circle a centripetal force. A centripetal force can be provided in a number of ways. See whether you can identify which of the forces below provides the force in each situation: