People use a variety of methods to wash clothes. Usually, after adding the soap, they 'beat' the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?

Soap molecules have two parts namely hydrophilic which dissolves in water and hydrophobic, that dissolves in hydrocarbons. With the help of these, it attaches to the grease or dirt particle and forms a cluster called micelle. These micelles remain suspended as a colloid, on the clothes and on being beaten or agitated, the particles are removed from the clothes surface and go into the water, thus cleaning the clothes.