RIGID BODY

RIGID BODY

Any real body, which we come across in daily life, has a finite size. Such 

an extended body consists of a system of particles. For the sake of

simplicity, we consider the extended bodies as rigid bodies.

Ideally a rigid body is that which has a definite size and definite shape. 

This is because   distances between different pairs of particles of such

 body do not change on applying any force on it However, no real body

 is truly rigid as real bodies deform under the action of forces applied

on them. But in many situations the deformations are often negligible.

For describing the motion of rigid body the key concept of "center of

mass" is very important. This concept enables us to understand how 

we can apply justifiably the Newton’s laws of motion.

Kinds of motion of a rigid body rigid body

A rigid body has three kinds of motion

A) Pure transnational - In such type of motion every particle of the body has the same velocity at a particular instant of time.

B) Pure rotational –In such type of motion a rigid body rotates about 

a fixed axis. Every particle of the body moves in a circle, which lies 

in a plane perpendicular to the axis, and has its center on the axis.

C ) Combination of translation and rotational motion

Note—The motion of a rigid body, which is not pivoted or fixed in some way is either a pure translation or a combination of translation and rotation.

The motion of a rigid body, which is pivoted or fixed in some way, is rotation.