Friction causes resistance in motion. It is also a force that acts in opposite direction of motion. When you put brake on your bicycle, it stops suddenly because you increase the friction between wheels and road. It is hard to push a box on cemented surface because cemented surface causes more friction due to its irregular surface and on other hand if push same box on glass table it will slide very easily because it has smooth surface that cause lower friction than cemented surface.
Types of friction
Friction has three types:
Static Friction occurs between objects that are in contact with each other are forced to move but both of them are not moving. That means if you put a box on a table or any surface and trying to push it but it is not moving than it feels static friction.
if one object is moving on another than both them are experiencing kinetic friction. Kinetic friction always occurs to moving objects. Normally kinetic friction is less than the static friction.
There are two types of kinetic friction
1. Sliding friction: When two objects slides on one another both feels sliding friction. Pushing a box and rubbing your hands both are examples of sliding friction.
2. Rolling friction: When one objects rolls on another or both are rolling on one another both feels Rolling friction. It is less than the Sliding friction that is why pushing a weight on wheels is easier than sliding it.
Like solids, liquids and gases also offer resistance in motion of an object. This kind of resistance is called Fluid friction. Drop a coin in oily liquid, it will sink slowly because of fluid friction. While riding a bicycle you feel backward push by air, it is also fluid friction.
In our everyday life friction is very important.
- It helps walking on the road.
- You warm your hand by rubbing them together.
- You driving a car and brake it for sudden stop.
- It helps you to hold a pencil or anything tightly.
Sometimes friction is avoided
- To reduce the loss of energy into machines.
- Our body joints are well lubricated to reduce friction.