Science (phy)

The force to keep a circular motion is named centripetal force(向心力).
Since centripetal force is always prependicular to the motion of object, no work is done. Remember : W = F x v, both force(F) and velocity(v) are vector and the symbol x does not only mean multiplication, it is the cross product!
Since no work is done, there is no energy change of the object due to the centripetal force. If no other external force is exerted on it, no change in energy of it.