Explain the procedure for separation of sand water into sand and water.

You are provided with a mixture of salt, sand, oil and water. Write the steps involved for the separation of salt, sand and oil from the mixture.

Amixture of sand and water is an example of

Explain how it is possible to separate gold from river sand.

A worker wishes to pile up sand on to a circular area of radius R. No sand is to spill on to the surrounding area. If mu_(s) is the coefficient of static friction of sand on sand,the sand pile . Density of sand =rho