Science

Friction

Question:

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.

Answer:

When a book slides on the writing desk, a frictional force acts between the book and the surface of the desk. The direction of frictional force on the book is opposite to the direction of its motion and acts in upward direction, as shown in the following figure.
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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.