3B Scientific Basic Mechanics Kit User Manual

U60020 Mechanics

Work sheet

Experiment 7 Rolling friction

Topics covered in the experiment

• When two surfaces rub against each other, there is a force that tends to oppose their relative movement.

• This frictional force can be reduced significantly through rolling.

Parts required:

From the Student Kit – Mechanics (U60020)

1 dynamometer
1 friction block
1 trolley
1 Aluminum weight

From the Student Kit – Basic Set (U60010)

1 Base plate

Procedure

1) Hold the dynamometer horizontally and adjust the pointer to zero.

Figure 1

2) Place the friction block with its rough surface in contact with the base plate and place the weight on the

friction block (see Figure 1).

3) Hook the dynamometer to the friction block.

4) Pull on the dynamometer and determine the tensile force that is needed to keep the friction block moving

slowly and uniformly on the base plate.

5) Note down the measured value in the measurement table.

Figure 2

6) Replace the friction block to the trolley, place the weight on the trolley and hook the dynamometer to it

(see Figure 2).

7) Pull the dynamometer and determine the tensile force required to keep the trolley moving slowly and

uniformly over the surface of the table, and note down the values in the measurement table.

8) Observe the movement of the trolley when you are no longer pulling on the dynamometer.

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Mechanics / Experiment 7 Work sheet 3B STUDENT Kit

Measurement table:

Tensile force in N

Friction block

with weight

1.30 0.06

Trolley with wheels

and weight

Analyze and explain the observations

a) Compare the tensile forces that need to be applied to the friction block and to the trolley before they just

begin to move.

The tensile force needed is much lesser in the case of the trolley with wheels than in the case
of the friction block.

b) What is meant by the force of rolling friction?

The force of rolling friction is the force that opposes the movement of a body that rolls on
wheels over a surface. It is the force that has to be applied to sustain the rolling motion.

c) What happens if the tensile force that is applied to the rolling trolley is withdrawn?

The motion of the trolley will be decelerated by the action of the force of rolling friction, till
it comes to rest.

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