The centripetal force is the force that a particle (or object) points to the center of curvature (the center of the circle) when it moves on a curve. When an object moves in a circle, the external force (or the component of the external force pointing to the center of the circle along the radius) is called centripetal force, also known as normal force. It is a centripetal force provided or acted by the resultant force. In addition, the centripetal force in the sense of group cohesion comes from the unity of opposites between the command authority of group leaders and the attitude of waiting for the next move.

Centrifugal force refers to the force that leaves the center of rotation due to the rotation of an object, and also refers to an apparent force in the rotating reference frame, which makes the object deviate radially outward from the axis of rotation. The value is equal to centripetal acceleration, but the direction is opposite.