Circular Motion

What is Circular Motion?

Circular motion is the motion of an object along a circular path around a fixed center. The object may move at constant speed, but its velocity changes continuously because its direction changes.

What is Radius in Circular Motion?

The radius, r, is the distance from the center of the circle to the object. Its SI unit is meter (m).

What is Angular Displacement in Circular Motion?

Angular displacement describes how much an object rotates around the center of the circle. It is commonly measured in degrees (°) or radians (rad).

One complete revolution = 360° = 2π rad.

What is Period in Circular Motion?

The period, T, is the time required for one complete revolution.

SI unit: second (s)

What is Frequency in Circular Motion?

Frequency, f, is the number of complete revolutions per second.

SI unit: hertz (Hz)

Formula:

f = 1/T

What is Linear Speed in Circular Motion?

An object moving in a circle has a linear speed along the circular path.

Formula:

v = 2πr/T

where r is radius and T is period.

What is Centripetal Acceleration in Circular Motion?

An object moving in a circle has acceleration directed toward the center of the circle. This is called centripetal acceleration.

Formula:

a = v²/r

The direction of centripetal acceleration continuously changes as the object moves around the circle.

What is Centripetal Force in Circular Motion?

The force that keeps an object moving in a circular path is called centripetal force. It always acts toward the center.

Formula:

F = mv²/r

where m is mass, v is speed, and r is radius.

Centripetal force is not a new type of force. It can be provided by tension, friction, gravity, or another force, depending on the situation.

What is Constant-Speed Circular Motion?

Even if an object moves at constant speed, it is still accelerating because its velocity changes direction.

For example, a car traveling around a circular track at constant speed is accelerating toward the center of the track.

What are the Important Facts about Circular Motion?

Circular motion involves a circular path, a radius, and motion around a center.

Centripetal acceleration and centripetal force always point toward the center.

Constant speed does not mean constant velocity because the direction is continuously changing.