Friction is a force that resists motion. The amount of friction depends on how an object is moved, such as sliding it or rolling it. In other words, it is a force that opposes the motion of objects whose surfaces are in contact with each other.
The goal of reducing friction is to make the surfaces of objects move more easily over one another. This is accomplished in several ways.
- Smoothing out surfaces
- Placing a slippery substance between two solid surfaces
- Applying wax between solid materials
- Using rotating objects such as roller bearings, ball bearings, and wheels
- Streamlining vehicles to reduce friction caused by air.