Friction is due to the roughness of surfaces. It can be reduced by the following methods.
1. By polishing the rough surface.
2. By applying lubricants like oil and grease to the surfaces.
3. By spreading powder on the rough surface like carromboard.
4. By using soap and detergent solutions, etc.
Experiment: The rusted pulley makes a rattling noise. Apply some oil in between the wheel and axle. The sound is reduced and now it works smoothly.
