The diagram shows a circular metal disc of mass 200 g, freely pivoted at its centre.
(diagram)
Masses of 100 g, 200g, 300 g, 400 g, 500 g and
600 g are available, but only one of each value.
These may be hung with string from any of the
holes. There are three small holes on each side of
the centre, one at 4.0cm from the pivot, one at
8.0 cm from the pivot and one at 12.0c from
the pivot.
The apparatus is to be used to show tharere is
no net moment of force acting on a body in it
is in equilibrium
a On a copy of the diagram, draw in to
different value masses hanging from
appropriate holes. The values of the tres
should be chosen so that there is no
moment. Alongside the masses choser rite
down their values.
[2]
b Explain how you would test that your
chosen masses give no net moment to
the disc.
[1]
c Calculate the moments about the pivot
due to the two masses chosen.
[2]

(Cambridge IGCSE Physics 0625 paper 31 Q2 November 2008)