A uniform metre rule of weight 10 gf is pivoted at its 0 mark.
(i) What moment of force depresses the rule?
(ii) How can it be made horizontal by applying a least force?

(i) Moment of force = Fr

Substituting the values of F and r we get,

10 × 50 = 500

In order to make the rule horizontal by applying least force distance has to be max as moment of force will remain same.

So,

F = 500\over 100 = 5 gf

Therefore, a force of 5 gf upwards at 100 cm can balance the rule.