Uniform Circular Motion

Introduction

In Physics, Uniform circular motion is an important topic in the IIT JEE examination syllabus. Therefore, candidates appearing for board examination or any national level examination will need to brush up their knowledge about uniform circular motion.

When an object moves in a circle at a constant speed, that phenomenon is called Uniform circular motion. As the object moves, it changes its direction constantly. The object moves in a direction tangential to the circle at all points along its motion

What is Uniform Circular Motion?

Uniform Circular Motion refers to the movement of an object at a constant speed in a circular path. The velocity of this moving object changes during each movement as the direction is constantly changing, however the speed is constant. 

In general, an object that moves in circles accelerates. Now, what is the meaning of acceleration of a moving object? Objects that accelerate usually change their velocity. This velocity change may be the result of the change in speed or direction.

An object that undergoes uniform circular motion is moving at a constant speed. The acceleration’s direction is towards the circle’s centre, i.e., inwards. So, the acceleration isn’t occurring due to the change in the speed. It occurs due to the change in direction. 

The moving object’s net force acts towards the centre of the circle during motion. This force has a name. It is called the centripetal force. In the absence of the centripetal force, the object would continue to move in a straight line. With this centripetal force acting perpendicular to the velocity vector, the moving object experiences an inward acceleration. This acceleration is due to the change in the direction of the object with every movement. 

Uniform Circular Motion Examples

An item travelling in a circle is gaining speed. Objects that are accelerating change their velocity – either the rate or the trajectory. An object in uniform circular motion moves at a constant pace. Despite this, it is speeding due to its shift, of course. The acceleration is pointing inwards. 

The net force is the ultimate motion characteristic of an item moving in a uniform circular motion. The net force acting on such an item is directed toward this circle’s centre. The net force is referred to as an inward force or centripetal force.

Here are some instances of uniform circular motion:

Uniform circular motion is demonstrated by :

• Electrons move around its atom.
• The movement of windmill propellers.
• The base of a watch, nearly new with a circular dial, exhibits consistent circular motion.
• The movement of artificial satellites around the Earth. The Earth’s gravitational field keeps the observatories in a continuous orbit around the planet.

What Is Centripetal Acceleration?

Centripetal acceleration is the attribute of an object’s velocity in a circular route. Centripetal acceleration refers to any item that moves in a circle and has an acceleration vector pointing towards the centre of that circle.

You’ve probably encountered several examples of centripetal acceleration in your daily life. When you drive a car in a cycle, you are experiencing centripetal acceleration, and a satellite circling the Earth similarly experiences centripetal acceleration. Centripetal refers to a movement toward the centre.

Centripetal Force

The force that keeps a body in uniform circular motion and provides the centripetal acceleration needed is known as centripetal force. It is a generalised term and can be caused by various methods. It may be friction, gravitational force, Electrostatic force, etc.

Example: When a car moving on a road performs uniform circular motion, the frictional force is the centripetal force.

The value of the centripetal force and acceleration are as follows:

ac= v2/R;

Where;

ac= centripetal acceleration

v=speed of the body

R= Radius of the circle of motion

Now the centripetal force is :

F= mac

Which is a direct consequence of Newton’s second law of motion.

Centrifugal Force

It is a force that is equal in magnitude and opposite in direction to the centripetal force. It is, however, a pseudo force and used in non-inertial frames to satisfy Newton’s laws of motion. The frame of the rotating axis is the one where the centrifugal force is applied and it preserves Newton’s laws. The rotating axis is constantly changing direction and hence is accelerated, implying it is a non-inertial frame.

Conclusion

Uniform circular motion occurs when a body’s motion follows a circular route around a fixed point. Uniform circular motion is a circular motion in which the body moves in a circular route with a constant/uniform speed. When an item travels in a circle, its direction is continually changing. The item is always travelling transverse to the circle. Because the velocity vector’s heading is the same as the orientation of the incident particle, the velocity vector is also tangent to the radius. Since the velocity is changing direction continuously, it has an acceleration pointing towards the centre of the sphere known as centripetal acceleration that is brought about by an external force call centripetal force.