Question

the porter are the symbols of hard work​

Answer 1

The causes of friction are molecular adhesion, surface roughness and the ploughing effect it is called Contact force. It is offered by . solids, liquids as well as by gases but it is maximum in the case of solids and least in the case of gases Every object has a rough surface, though the surface may appear to be smooth to the naked eye. But when we observe through a microscope, we find that the surfaces of all the objects have rough edges. Some of the particles on the surface of objects are in the form of tiny hills and valleys.