We often come across advertisements of tyres where bikes stop immediately when the brakes are applied without any time lag. Also, most of us must have seen children playing with cycle tyres, rolling them across the floor with a stick. And remember when our parents used to pull the bag of luggage across the floor when looking for a taxi when we were all set for a vacation?

But how do phenomena like these and many others work? How are we able to walk and run? How is a bus able to move smoothly on the road?

The phenomenon at work here is friction. An important characteristic of friction is that it always opposes the applied force. When we apply force on an object in the left direction, the friction acts in the opposite, i.e. the right direction and that is the reason why pushing or pulling heavy boxes across the floor comes out as a strenuous task.

What factor affects friction?- Just as no human is perfect, similarly no object is devoid of irregularities. A glass slab that may look completely new, smooth, and shiny too contains a large number of irregularities on its surface. It is these irregularities that cause friction to come into play. Irregularities on the two surfaces lock into each other and when we have to move any object, we have to apply a force large enough to break the interlocking of the surfaces. The force required to overcome friction at the instant an object starts moving from rest is a measure of static friction. On the other hand, the force required to keep the object moving at the same speed is a measure of sliding friction.

Friction: A necessary Evil – It might seem that friction is not important and it only creates hurdles such as in moving objects. But that is not the case. Friction indeed plays an important role in carrying day-to-day activities.

Given below are few pointers that prove that friction might be evil, but is a necessity.

  1. Stopping moving objects– If there were no friction, an object that once started moving or was once set into motion, would never stop. The concept of ‘irregularities’ helps stop a moving object.
  2. Vehicles to be driven– It is due to friction that we can move forward and backward our vehicles.
  3. It would not have been possible to hammer a nail or tie a knot if there were no friction.

Demerits of friction –  Friction alongside playing the role of friend also has some demerits. It is responsible for the wearing out of materials whether they are screws, ball bearings, or soles of shoes. Friction also produces heat which can be both useful as well as dangerous.

Is it in our control to increase or decrease friction? Sure it is.

This can be done by using treaded tyres in vehicles for a better grip. The use of lubricants also makes surfaces smooth to some extent (not wholly though) and form a thin layer thereby preventing the two rough surfaces to come in contact. 

Friction is both, a friend and foe and it is inevitable.

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