Define rigidity.

Hint: We will answer this question by knowing about changes in the dimensions of the solid body when different factors change. When a large force acts on any solid body it changes its shape. But for small forces , the solid body does not change its shape, this is what explains what rigidity is.

Complete answer:
Let’s start with the definition of a rigid body: a body which doesn’t undergo change in its shape and size, when external forces are applied on it , is called a rigid body. And this property of the body to prevent undergoing any change in its shape and size is called rigidity.
Solids are the best examples of rigid bodies. The reason for the same is that the particles in a solid body are closely packed and they have strong intermolecular forces of attraction.

Additional information:
Rigid bodies have certain characteristics:
1) The deformation in rigid bodies is 0.
2) A rigid body is usually considered as a continuous distribution of mass.
3) The distance between any 2 particles in a solid is constant.

Note: 1) Remember that the distance between any 2points /particles in a rigid body is constant irrespective of the amount of force exerted on it if this distance changes the body is not rigid. Nobody is perfectly rigid. There is a difference between hard bodies and rigid bodies. Rigid means:bodies do not undergo deformation, but hard means: the resistance applied by the body against the pressure that is applied to it does not treat both as the same.