Introduction to Friction

When we kick football, we observe that ball comes to rest after sometime

Or when we stop pedaling the bicycle, it automatically comes to rest

So there is some unseen force is acting on them which is holding back their movement

This unseen force is known as friction.

Friction is the force which holds back the movement of a moving object.

Friction is the resistance to motion of one object moving relative to another.

The frictional force acts in the opposite direction.

For example we can walk without slipping because of friction only.

When we are moving in forward direction then friction is acting in backward direction.

But friction depends on the nature of the medium like the roughness and smoothness of the surfaces

On the smooth surfaces friction is less compared to rough surfaces, we feel slippery and fall.

If there is more roughness then friction increases.

And we feel very hard to move

Causes for Friction

Every object has a rough surface, even though the surface may appear to be smooth to our eyes

when we see through microscope, we can observe rough edges, these are called irregularities of surfaces.

Interlocking of irregular surfaces, opposes the motion of one object over the other and give rise to force of friction

Friction is caused by the interlocking of irregular surfaces of two objects which are in contact with each other.

REVISION

Friction is the resistance to motion of one object moving relative to another.

Friction depends upon the nature of medium.

END