Chapter 1, Problem 1CP

What is a fluid? How does it differ from a solid? How does a gas differ from a liquid?

To determine

The definition of fluid.

The difference between solids and fluids.

The difference between gases and fluids.

Explanation of Solution

A fluid is substance which can flow under the action of the shear force. The examples of the fluid are given below:

Liquid, gas, vapor.

In solid state, the molecules of a substance are tightly bound to each other as the molecules have a fixed position in space. A solid exhibits rigidity and distinct shape. The intermolecular distance in a solid state is the least while the intermolecular force of attraction is the strongest.

Solids regain original shape if the shear force is within elastic limit when, the force is removed. But fluid never regains original shape after the removal of force.

Gas molecules are in a state of random motion. They exhibit the least intermolecular force of attraction and gases lack a definite shape. The intermolecular distance is very large due to which the particles of gases are widely separated from each other. The density and viscosity of gas is less compared to solid and liquid. Gas molecules are highly vulnerable to change in temperature and pressure.