Science

Friction

Question:

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

Answer:

Advantages of friction:
(i) We are able to walk because of friction.
(ii)Friction between the tip of the pen and a paper allows us to write. Disadvantages of friction:
(i)Tyres and soles of shoes wear out because of friction.
(ii) Friction between the different parts of machines produces heat. This can damage the machines.
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Friction

Q 1.

static, sliding, rolling

Q 2.

wet marble floor, dry marble floor, newspaper and towel

Q 3.

Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.

Q 4.

Explain why sliding friction is less than static friction.

Q 5.

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?

Q 6.

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

Q 7.

You spill a bucket of soapy water on a marble floor accidentally. Would it make it easier or more difficult for you to walk on the floor? Why?

Q 8.

Explain why objects moving in fluids must have special shapes.

Q 9.

Explain why sportsmen use shoes with spikes.