Chapter 11, Problem 1CQ

What physical characteristic distinguishes a fluid from a solid?

To determine

What physical characteristic distinguishes a fluid from a solid?

Answer to Problem 1CQ

The physical characteristic that distinguishes a fluid from a solid is that solids have a fixed volume and fixed shape while liquids only have a fixed volume but no fixed shape.

Explanation of Solution

Introduction:

Solid, liquid, gas, plasma and Bose-Einstein condensate are the five states in which mater exists.

The various states in which matter exists are distinguished on the basis of the structure and density of the particles comprising it.

In solids, the constituent particles are arranged in a regular and fixed pattern and are tightly bound to each other by the attractive forces which are strong in nature. As a result, solids have a fixed volume and also a fixed shape. Hence they do not deform easily under stress and resist shearing forces.

However, in the case of liquids, the constituent particles do not follow a fixed pattern and the attractive forces between them are also not as strong as in the case of solids. As a result, although liquids have a fixed volume but they do not have a fixed shape and hence they take the shape of the container in which they are kept. Hence they deform when a force is applied to them and yield on application of shearing forces.

Hence the distinguishing physical characteristic between solids and fluids is having a fixed volume but not a fixed shape.

Conclusion:

Hence, solids have a fixed shape and fixed volume while liquids have only a fixed volume and no fixed shape and this is the physical characteristic that distinguishes them.