Answer: The constant force that acts on the body along the radius towards the centre and perpendicular to the velocity of the body is known as centripetal force.
Let us consider an object of mass m, moving along a circular path of radius r, with an angular velocity ω and linear velocity v.
F = (mv2)/r
Again, centripetal force, F = mrω2 [( since v = rω )
1. In the case of the stone tied to the end of a string and rotated in a circular path, the centripetal force is provided by the tension in the string.
2. When a car takes a turn on the road, the frictional force between the tyres and the road provides the centripetal force.
3. In the case of planets revolving round the sun or the moon revolves around the earth, the centripetal force is provided by the gravitational force of attraction between them.
4. For an electron revolving around the nucleus in a circular path, the electro static force of attraction between the electron and the nucleus provides the necessary centripetal force.
The force, which is equal in magnitude but opposite in direction to the centripetal force is known as centrifugal force.
In the first example (stone), not only is the stone acted upon by a force (centripetal force) along the string towards the centre, but the stone also exerts an equal and opposite force on the hand away from the centre along the string.
1. While churning curd, butter goes to the side due to centrifugal force.