Element of survey:

You may recall from your school physics course that matter exists in any one of the three states that are known as solid, liquid and gas. At the atomic level, these states of matter are distinguished from each other in terms of the nature of bonding among their atoms or molecules. In solids, atoms or molecules are strongly bound to each other and are almost fixed at their positions. In liquids, atoms or molecules are not bound to each other as strongly as in the case of solids and they are somewhat free to move inside the whole mass of the liquid. In gases, atoms or molecules are not bound to each other and are completely free to move around in the entire volume of the container. Because of unique nature of their atomic or molecular bondings, solids, liquids and gases possess characteristics macroscopic properties. In this unit, you will study some of these properties of matter such as surface tension, viscosity, hydrostatic pressure and elasticity. These properties have wide ranging applications in engineering, organization and even in our day-to-day lives.

Due to weaker intermolecular forces, the molecules of a liquid could move about freely. This gives rise to surface tension - a characteristic property of stationary liquids which helps us understand phenomenon like the formation of water droplets, how the mosquitoes stand and walk on still water, and why mercury spreads in the form of spherical globules on the flat ground.

One of the important discoveries of science is that fluids - liquids and gases - exert pressure. We talk of hydrostatic pressure within case of liquid at rest and atmospheric pressure in case of air in our atmosphere. This property of fluids has contributed significantly in the industrial progress and sophistication in machines.

You will learn the characteristics of fluids at rest; you will study viscosity - a property of fluids in motion - which is a measure of fluids' resistance to flow. Knowing of viscosity enables us to explain lubrication, fluid flow in pipes or blood vessels and sedimentation rates.