Question

Why are ball bearing used ?

Answer 1

Ball Bearings reduce the friction of certain moving parts by replacing sliding friction with rolling friction. They are used to provide better linear motion or rotation around a fixed axis. Roller bearings are cylinders similar to free rollers, while ball bearings are spheres that are held in a track.

Answer 2

Ball bearings are used in different applications mainly they are used to reduce friction..
There are many examples in which you can see ball bearing they are mostly used where there is less load..
eg: Skateboards.. see the pic above