|Class 8 Physics Friction||Factors affecting Friction|
As we studied in the previous case, friction is caused by the interaction between the surfaces which are in contact. Friction is caused by the irregularities on the two surfaces which are in contact. The irregularities on both surfaces tend to lock into each other and this resists the motion of the object. The nature of the surface (smoothness or roughness) affects the friction.
Smooth surfaces have lesser irregularities. The lesser the irregularities, the lesser the tendency to lock. The lesser the tendency to lock with another object, the lesser the friction (that is tendency to oppose motion). And so, a ball rolls faster and covers a greater a distance on a smooth surface such as a marble floor or a wet floor. Think of the bowling game.
Rough surfaces have more irregularities. The more the irregularities, the more tendency to lock. The more the tendency to lock, the more the friction (that is tendency to oppose motion). And so, a ball rolls slowly and covers a lesser distance on a rough surface such as muddy play ground. Think of a rough muddy playground. So, it obviously means that to get the ball rolling we have to apply a force which is greater than the frictional force offered by the ground.
This also explains why we cannot hold a glass with oily hands. Our hands are greasy and smooth and we know that smooth offers lesser interaction or lock with the glass. And hence it tends to slip.
While trekking on hilly and watery terrains, we wear groovy sports shoes so that rough shoes establish better locking with the hilly trains, increase friction, provide more grip and decrease chances of a slip.