i. Force acting on a particle performing circular motion along the radius of circle and directed towards the centre of the circle is called centripetal force.

It is given by F_CP = \(\cfrac{m\text v^2}r\)

where, r = radius of circular path.

ii. Example: Electron revolves around the nucleus of an atom. The necessary centripetal force is provided by electrostatic force of attraction between positively charged nucleus and negatively charged electron.

iii. Unit: N in SI system and dyne in CGS system.

iv. Dimensions: [M¹ L¹ T^-2]

and 

i. A stone tied at the end of a string is revolved in a horizontal circle, the tension in the string provides the necessary centripetal force. It is given by equation T = mrω².

ii. The planets move around the sun in elliptical orbits. The necessary centripetal force is provided to the planet by the gravitational force of attraction exerted by the sun on the planet.

iii. A vehicle is moving along a horizontal circular road with uniform speed. The necessary centripetal force is provided by frictional force between the ground and the tyres of wheel.

iv. Satellite revolves round the earth in circular orbit, necessary centripetal force is provided by gravitational force of attraction between the satellite and the earth.