Normal reaction acting normal to the surface of the body in ____ direction.

The force of friction is always parallel to the two ____

Static friction is always equal to 

Generally co-efficient of friction is 

A force which acts at the surfaces of contact, when one body is made to slide upon another body is known as 

Force of friction can 

The force which opposes the relative motion of a body over another is called 

The force of friction is always 

The bodies of fast moving vehicles are streamlined so that 

With increase of temperature, friction