Centrifugal Force – Definition, Formula and Unit
Centrifugal force is a force that arises when a body is moving actually along a circular path, by virtue of tendency of the body to regain its natural straight line path.
It is our experience that whenever a bus takes a turn, the passengers sitting in the bus start experiencing a force, which tries to throw them away from the center of the curved path. In the same manner, children sitting in a merry-go-round experience outward force as the merry-go-round moves along the circular path.
This outward radial force experienced by an object, when in circular motion, is called centrifugal force.
The centrifugal force is due to the inertial property of the material bodies. We know that when a bus accelerates, the passengers in the bus experience force in the backward direction, and they get pressed against the back of their seats.
On the other hand, when a bus retards, the passengers experience a force in the forward direction, which makes them fall ahead. In fact, it happens due to inertia. It follows that the passengers in the bus experience a force in a direction opposite to that in which the velocity of the bus changes. Likewise, when a bus moves along a circular path and its velocity changes along the radius towards the center of the circular path, due to inertia, the passengers experience a force along the radius but away from the center.
Centrifugal Force Formula
The magnitude of the centrifugal force acting on a body of mass $M$ moving with velocity $v$ along a circular path of radius $r$ is the same as that of the centripetal force required to move the body along the circular path. Hence, centrifugal force acting on the body is also given by
\[
\boldsymbol {F = \frac{M v^2}{r} = M \omega^2 r}
\]
where $ \displaystyle \omega $ is the angular velocity.
The centrifugal force is not a real force. As we cannot identify its source, it is called a fictitious force or pseudo force. As discussed above, the passengers inside the bus simply participate in rotation. When the bus takes a turn and experiences centrifugal force, the centrifugal force can be understood in terms of inertia, but actually, inertia is not the source of this force.
Centrifugal Force and Centripetal Force
Centrifugal force can be regarded as the reaction of centripetal force. As forces of action and reaction are always equal and opposite, therefore, the magnitude of centrifugal force is equal to that of centripetal force. However, the direction of centrifugal force is opposite to the direction of centripetal force. Centrifugal force acts along the radius and away from the center of the circular path.
For example, when a piece of stone tied to one end of a string is rotated in a circle, centripetal force $\displaystyle {{F}_{1}}$ is applied on the stone by the hand. In turn, the hand is pulled outwards by the centrifugal force $\displaystyle {{F}_{2}}$ acting on it, due to tendency of stone to regain its natural straight line path.
Centrifugal Force Examples
The concept of centrifugal force has wide applications. Following are a few of such applications which illustrate the utility of centrifugal force:
- The application of centrifugal force is used to separate cream from the milk in cream-separators.
- The wet cloths are dried by dry-cleaners in the drying machines.
- Centrifuges are used to separate honey from the wax.
