Friction:
In the preceding units, it was assumed that the surfaces in contact were smooth and the forces between the bodies acted normally to the surface of contact. However, in practice, it is impossible to have perfectly smooth surfaces. There always present microscopic roughness which tends to prevent any possible sliding motion between the two bodies. In this unit, you will learn the laws governing the dry friction formulated by Coulomb, and their applications in different situations. You shall study the relation between the normal and frictional forces at a point of contact between any two non-lubricant rigid bodies. You will also study the frictional forces operating in various devices such as inclined plane, wedges, screws, belts and rope drives. The study of frictional forces is essential to solve the practical problems in Engineering Mechanics.
Objectives
After studying this unit, you should be able to
- understand the laws of dry friction,
- find out the magnitudes of frictional forces in different situations,
- work out friction-related quantities such like as coefficient of friction, angle of
- friction, angle of repose to solve problems involving dry friction, and
- Apply the laws of friction to various devices like inclined plane, wedges, screws, belts and rope drives.