Question

A brick is attached to a spring balance.
You pull the brick (a) without wrapping polythene on it and (b0 by wrapping polythene on it. Discuss the reading in the two cases.

Answer 1

Answer:

Tie a string around a brick. Pull the brick by a spring balance Fig. You need to apply some force. Note down the reading on the spring balance when the brick just begins to move. It gives you a measure of the force of friction between the surface of the brick and the floor.

Now wrap a piece of polythene around the brick and repeat the activity. Do you observe any difference in the readings of the spring balance in the above two cases? What might be the reason for this difference? Repeat this activity by wrapping a piece of jute bag around the brick. What do you observe?

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