What is Circular Motion?
When an object moves along the circumference of a circle, its motion is called circular motion.
Even if the speed remains constant, the direction of motion keeps changing at every point. Because of this continuous change in direction, circular motion is an accelerated motion.
Simple Definition
Circular motion is the motion of an object along a circular path with constant or variable speed.
Everyday Examples of Circular Motion
You see circular motion around you every day:
- Rotation of a ceiling fan
- Stone tied to a string and whirled in a circle
- Hands of a clock
- Satellite revolving around the Earth
- Car taking a circular turn on a road
Why Circular Motion is Not Uniform Motion
In straight-line motion, both speed and direction can remain constant.
But in circular motion:
- Speed may remain constant
- Direction always changes
Since velocity depends on both speed and direction, changing direction means velocity changes.
Therefore, circular motion is always accelerated motion.
Velocity in Circular Motion
At any point in circular motion:
- Velocity acts along the tangent to the circle
- It is perpendicular to the radius
Important point:
Velocity never acts towards the centre of the circle.
Force Required in Circular Motion
An object moving in a circle needs a force that:
- Always acts towards the centre
- Changes the direction of velocity
This force is called centripetal force.
Example
- In stone tied to string → Tension
- In planets → Gravitational force
- In car turning → Friction
Circular Motion Topics
- Focus on concepts
- Understand why force is required
- Learn real-life examples
- No heavy formulas needed
- Angular displacement (θ)
- Angular velocity (ω)
- Centripetal force formula
F = mv² / r
This chapter forms the foundation for mechanics.
- Banking of roads
- Satellite motion
- Vertical circular motion
- Rotational mechanics
Concept clarity here helps in JEE & NEET.
Common Mistakes Students Make
Thinking circular motion is uniform
Assuming velocity is towards centre
Mixing centripetal and centrifugal force
Ignoring direction change of velocity
Summary
- Circular motion occurs along a circular path
- Direction of velocity keeps changing
- Circular motion is always accelerated
- Centripetal force is necessary to maintain circular motion
FAQs on Circular Motion
Is circular motion accelerated motion?
Yes, because direction of velocity changes continuously.
Can speed be constant in circular motion?
Yes, but velocity cannot be constant.
What happens if centripetal force is removed?
The object moves in a straight-line tangential path.
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