Question

What is the difference between solid and fluid?

Answer 1

Definition

1. The solid has become one of the $4$ fundamental states of matter wherein the molecules have been tightly packed collectively as well as have the least amount of kinetic energy (K.E).
2. Fluid has been defined as a material that constantly deforms when subjected to the shearing force of any magnitude.

The difference between solid and fluid

Fluids	Solids
1.Fluids have no shape	1.Solids have a definite shape
2.Fluids cannot sustain a shear force, a fluid is always in motion.	2.Solids can sustain a shear force, they remain static.
3.Because stress seems to be a function of strain rate, fluid has a 'dynamic' condition.	3.Because stress is proportional to strain, a solid retains a static or 'quasi-static' condition.
4.A fluid's static characteristics cannot be transferred just to dynamic properties.	4.A solid's static attributes could be expanded to dynamic properties.