Oil, grease and ball bearings are used to

• increase friction

• decrease friction

• regulate friction

• streamline friction

Explain why sportsmen use shoes with spikes.

Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?

Explain why sliding friction is less than static friction.

Give examples to show that friction is both a friend and a foe.

Explain why objects moving in fluids must have special shapes.

What is force of friction?

What is the cause of friction between two surfaces?

Which is small sliding friction or static friction?

Which force helps to write by chalk on black board?

Why is it difficult to move on a wet marble floor?