In uniform circular motion there is no change in magnitude of velocity, but there is only change in direction of velocity.
Hence uniform circular motion is an accelerated motion According to Newton's second law of motion, there are must be a force acting on body to produce an acceleration. This force must act in the direction of acceleration, i.e. along radius and directed towards the centre. Such a force acting on particle performing circular motion is called as centripetal force. Centripetal force is necessary for particle to perform circular motion.
Defi : Centripetal force is force acting on particle performing circular motion., which is along radius of circle and directed towards the centre of circle.
Since centripetal force acts at right angles to the tangential velocity of particle, there is no displacement in the direction of force, hence no work is done by centripetal force.
As per Newton's second law of motion.
Force = mass x acceleration
Where m - mass of particle performing U.C.M.
The S.I. unit of centripetal force is newton (N).
In nutshell, the centripetal force.
* Is the real force acting on particle performing circular motion.
* Is a necessary force for maintaining circular motion.
* Its direction is different points.
* Acts along the radius of circle and directed towards the centre of circle.
* Does no work.
Examples :
1) When an object tied at the end of a string is whirled in a horizontal circle, the necessary centripetal force for maintaining circular motion is provided by tension in the string.
2) If a car is travelling round a circular hozizontal road with uniform speed, the necessary centripetal force for negotiating the curve is provided by force of friction between tyres of vehicle and road surface.
3) In case of a train negotiating the curve, the necessary centripetal force is provided by push due to rails on the wheels of a train.
4) The electrons revolve in permitted circular orbits around the nucleus of an atom. Here the necessary centripetal force is provided by electrostatic force of attraction between positively charged nucleus and negatively charged electron.
5) Moon revolves around the earth in a circular orbit. Here the necessary centripetal force is provided by gravitational force of attraction between moon an earth.