Types of Mechanical Forces

A force exerted on a body can cause a change in  either the shape or the motion of the body. The  unit of force in SI system is the newton (N) and  CGS system is dyne. No solid body is perfectly  rigid and when forces are applied to it, changes in  dimensions occur. Such changes are not always  perceptible to the human eye since they are  negligible. For example, the span of a bridge will  sag under the weight of a vehicle and a spanner  will bend slightly when tightening a nut. It is  important for civil engineers and designers to  appreciate the effects of forces on materials,  together with their mechanical properties of  materials. There are three main types of  mechanical forces that can act on a body. They  are:
1. Tensile force  2. Compressive force and  3. Shear force