# Uniform Circular Motion

What is Uniform Circular Motion?

The movement of a body following a circular path is called a circular motion.

Uniform Circular Motion is the term used to describe a body moving in a circular path at a constant speed. While the velocity in this case changes, the speed is constant.A particle must be experiencing some acceleration toward the centre of the circle if it is rotating around that point. Since this acceleration is always perpendicular to the particle’s instantaneous velocity, it only modifies the direction of velocity, not its magnitude, leading to uniform circular motion. This acceleration is referred to as centripetal acceleration (also known as radial acceleration), and the force pulling in that direction is known as centripetal force.

We know that the circumference of a circle of radius r is given by 2 r π . If the athlete takes t seconds to go once around the circular path of radius r, the speed v is given by
v = 2 r π / t
When an object moves in a circular path with uniform speed, its motion is called uniform circular motion.

n the case of uniform circular motion, the acceleration is:

a = v2/r = ω2r

If the mass of the particle is m, we can say from the second law of motion that:

F = ma

mv2/ r= m ω2 r

This is not a special force, actually force like tension or friction may be a cause of origination of centripetal force. When the vehicles turn on the roads, it is the frictional force between tyres and ground that provides the required centripetal force for turning.

Examples of Uniform Circular Motion

Following are the examples of uniform circular motion:

Motion of artificial satellites around the earth is an example of uniform circular motion. The gravitational force from the earth makes the satellites stay in the circular orbit around the earth.
The motion of electrons around its nucleus.
The motion of blades of the windmills.
The tip of second’s hand of a watch with a circular dial shows uniform circular motion.