Rotational Motion Of Rigid Body MCQ - Practice Questions with Answers

• Rigid body-

It is defined as a system of particles in which the distance between each pair of particle remains constant.

This means the shape & size do not change during the motion.

• Translation motion- 

If a body is moving such that a line drawn between any two of its internal points remain parallel to itself.

All the particles of the body move along parallel paths.

All the particles of the body follows 1 D motion.

Example- Motion of a body along a straight line.

• Rotational motion-

A rigid body is said to be in pure rotation if every particle of the body moves in a circle and centre of all the circles lie on a straight line called the axis of rotation.

The line joining any two internal points does not remain parallel.

Example-motion of wheels, gears, motors.

• Some important terms-

1. System-

A system is a collection of any number of particles interacting with one another and are under observation for analysing the situation. 

2.  Internal forces-

Internal forces are all the  forces exerted by various particles of the system on one another . Internal forces between two particles are equal in magnitude and opposite in direction.

3. External forces-

External forces are the forces that we have to apply on the object/system from outside to move or stop an object/system.