# Science Site

## What is Friction?

Published on Jul 15, 2016

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Everyone wants to their work done as fast as possible so that they can spend time in leisure activities or for other work that they think is important. When we are driving a car or a cycle, we want to go as fast as possible so that we can reach our destinations in as little time as possible. And we all dislike braking for an unnecessary traffic jam caused by a stray animal on the road. Have you ever wondered why the vehicle slows down and stops when brakes are applied?

### Friction is a force

Suppose you place a dictionary on a table and push it away from you. As you are pushing the bulky dictionary, you notice that the force that you are supplying is being opposed by some other force. At first you might think that it is actually the weight of the book which makes it difficult to push on a table. But weight is applied directly downwards, towards the center of the earth. In fact, it is another force called friction which is applied in a direction opposite to which you are applying the force on the book to push it. Force of friction tends to work in an opposite direction. This is a direct consequence of Newton’s third law of motion which states that every action has an equal an opposite reaction.

### What causes friction?

Friction is caused by the irregularities in the texture or the roughness of the surface at any level of consideration, from visible to naked eye to microscopic. If a surface is completely smooth, it will never experience friction. The irregularities cause the objects that are in touch with the surface to interlock with the surface. In this way, whenever we wish to move an object on the surface, we will have to apply enough force to overcome friction. If an object started moving, it would never stop moving if the surface was completely frictionless. This is a consequence of the first law of motion which states that an object at rest and an object in motion will continue to retain their states, unless compelled by an external force to do so.

### Is friction good or bad?

Friction is both, good and bad at different that. Friction is good when it aids us in accomplishing our tasks and making life easier for is. For example, the vehicle you drive would not be able to go anywhere if there was no friction. It is due to friction that wheels of the car attain the required motion. It is due to friction that you are able to stand up straight on the ground instead of falling over again and again as if you were wearing roller skates. But friction is bad when it comes to dealing with machinery having moving parts. Due to friction, the moving parts of a machine like gears are subject to wear and tear. Friction present due to air is bad when a plane is taking off because it resists the motion of the plane through air and makes it difficult for the plane to attain height.