Page 80 - Physics - XI

ACTIVITY - 4

Aim

To measure the force of limiting friction for rolling of a roller on a horizontal plane.

Apparatus and Materials Required

A wooden block with a hook on one side, a horizontal plane fi tted with a pulley at one of its ends, a light
weight pan, thread, a spring balance, a weight box, set of weights, lead shots (rollers), and a spirit level

R (Normal reaction)

Wooden block Standard weights (w)

Rollers T = (x + x ) g Pulley
2
1
F
r T

w′ + w Table Scale
pan

Standard weights (x + x ) g
2
1
Fig. 4.1: Experimental setup to study the rolling friction

Principle/Theory
Rolling friction: The opposing force which comes into play when a body rolls or tries to roll over another
surface of another body is called rolling friction. Rolling friction is less than sliding friction.

Procedure
1. With the help of a spirit level, check the horizontal surface and spread a layer of lead shots on it.
2. After checking the horizontal surface, measure the weight of the wooden block with the help of a
spring balance.

3. Determine the weight of the pan.
4. Now, add a small weight to the pan and notice that whether the wooden block kept on rollers starts
moving or not.

5. If the block does not start rolling, then add some more weights to the pan.
6. Repeat step (4) till the block just starts moving.
7. When the block starts moving, note the total weight of the pan.
8. Now, put some suitable weight over the wooden block and repeat the above step (5) to (7) and note the

respective weights in the observation table.
9. Repeat the process and increase the weights in steps over the wooden block and pan and then note the
value of weights in the observation table.
10. Calculate the mean value of total weight (force) pulling the block and weights and record it.

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