Question

what is ball bearing? how does a ball bearing reduce friction​

Answer 1

Answer:

Ball bearings are some type device of two rolling elements surfaces which are separated by small metal balls so as to reduce the friction and let the rolling surfaces slide as smoothly as possible over each other rolling surfaces.

You'll find ball bearing wherever there are machine rolling surfaces that slide over each other. Balls are put in between these surfaces to reduce the friction so that the machine will last long with less wear and tear.

The reason to use balls is that they

1. Reduce contact surface area between two rolling surfaces

2. Rolling friction is less than sliding friction.