Fluid Friction
You know that air is very light and thin. Yet it exerts frictional force on objects moving through it. Similarly, water and other liquids exert force of friction when objects move through them. In science, the common name of gases and liquids is fluids. So we can say that fluids exert force of friction on objects in motion through them. The frictional force on an object in a fluid depends on its speed with respect to the fluid. The frictional force also depends on the shape of the object and the nature of the fluid. It is obvious that when objects move through fluids, they have to overcome friction acting on them. In this process they lose energy. Efforts are, therefore, made to minimize friction. So. objects are given special shapes. Where do you think the scientists get hints for these special shapes? From nature, of course. Birds and fishes have to move about in fluids all the time. Their bodies must have evolved to shapes which ould make them not to lose much energy in overcoming friction. You read about these shapes in Class VI. Look carefully at the shape of an aeroplanes Do you find any similarity in its
Notes
Friction - Notes
