The diagram alongside shows a uniform metre rule of weight 100 gf being balanced on a knife edge placed at the 40 cm mark, by suspending a weight w gf at the mark 20 cm, find:

the position of another weight of 50 gf to balance the rule in part (ii).

Explanation

To balance the metre rule in part (ii), a clockwise moment is required for which the weight 20 gf is to be kept on right side of knife edge at distance x cm (say). Then
`20gfxxxcm=500gfcm` or x = 25 cm
Thus the weight 20 gf is to be suspended at the mark 40 + 25 = 65 cm