Question

what is centripetal force? and how is centripetal force operating ?

Answer 1

http://en.wikipedia.org/wiki/Centripetal_force

Answer 2

Centripetal force is any force or component of force that is required to keep a body on a non linear path.

This force is normal to the path and directed towards the centre of curvature, hence its name.

This force provides the normal centripetal acceleration that allows the path to be curved.

In case of steady circular motion of radius R of a body of mass m, the intensity of the normal force is mv²/R, directed towards the centre of the circle.
No other force is needed for this motion.
As the force is normal to the velocity of the body, no work is done and the kinetic energy of the body and its velocity are constant.

This force can result from a tension in a string, a normal force, a friction force, a gravitational force, or a combination of those.

Answer 3

That's what keeps you on a curve motion instead of flying away tangentially, bro