Circular motion is movement along a circular path or a circular orbit. A body describing a circle is not at rest. It does not move with constant velocity because whether the speed is changing or constant, the direction of the motion continuously changes. From Newton’s First Law, a resultant force must be acting on the body, and from his Second Law this force equates mass times acceleration so the body must be accelerating.
E.g. the moon describes a path around the earth. The force which the earth exerts upon the moon is the force of gravity which pulls the moon towards the earth. If this force did not exist the moon would move off at a tangent to its’ path around the earth. This phenomenon also applies to a satellite orbiting the earth; and electrons orbiting the nucleus with a force of the positive protons acting on them.
