Question

A uniform metre scale is kept in equilibrium when supported at the 60cm mark and a mass M is suspended from the 90cm mark as shown in the figure. State with reasons, whether the weight of the scale is greater than, less than or equal to the weight of mass M.

Answer 1

Let M be load.

∴ Load arm = 90 – 60 = 30 cm

Since wt. of scale will act at centre of gravity of scale which is the midpoint of the scale.

∴ Effort arm = 60 – 50 = 10 cm

Let wt. of scale be W

By principal of moments L × dL = E × dE

M × 30 = W × 10 W = 3M

∴ Since weight of scale is three times that of M.

∴ Weight of scale is greater than weight of M.