Always opposes the direction of a moving object

Type of surface & mass of object

Smooth surfaces produce small frictional forces

Heavy objects produce large frictional forces

Produces heat, slows down a moving object and stops it, holds an object, makes an object stay static, sharpens tools

Produces unwanted noise, makes movement difficult, causes the soles of shoes and tyres of vehicles to be worn out

Use patterned soles and surfaces, make the surface rougher, use anti-slip mats, use magnesium carbonate chalk powder

Use lubricants, use grease, use rollers and ball bearings, use wax, use boric acid powder