Question

what is the expression or centrpetal force? ​

Answer 1

There is no formula for the centripetal force in terms of radius and mass, because centripetal force is the cause of an object moving in a circle. The centripetal force arises from some other cause, e.g. gravitation, electrostatic, our muscles pulling on a rope, … This produces a centripetal acceleration, given as usual by a = F/m. This acceleration, in turn, determines the radius at which the body rotates through the formula a = v2/r.

Answer 2

The force acts of object moving along a circle it is called centripetal force.