Define friction. What are the factors affecting friction? Explain with examples.

What is the cause of friction? Explain with the help of a labelled diagram.

Give examples to show that friction depends on the nature of two surfaces in contact.

Give an example to show that friction depends on the force with which the two surfaces are pressed together.

What is the difference between static friction and sliding friction? For' a given pair of objects, which of the two is greater?

How can a very heavy machine be moved conveniently from one place to another in a factory? (No crane is available for this purpose).

What is drag? Give two examples of a drag force.

How can you reduce the drag on something moving through the air?

What is meant by 'streamlined shape'? Name an object which usually has a streamlined shape.

Explain why, objects moving in fluids should have streamlined shape.