Question

A heavy metallic scale of length 1 m has its centre of gravity at 50 cm division. It is suspended at a 30 cm mark. A load of `60 gwt` has to be tied at its zero cm make to keep it in equilibrium. Calculate the weight of the scale.

Answer 1

The scale is in equilibrium. Thus, according to the principle of moments, the sum of clockwise moments `(W_(1)l_(1))` is equal to the sum of anti-clockwise moments `(W_(2)l_(2))`.

`:. W_(1)l_(1)=W_(2)l_(2)`
`W_(1)=` weight of the scale.
`l_(1)=` distance of centre of gravity of the scale from the point of suspension
`=50-30=20 cm`
`W_(2)=` load=60 gwt
`l_(2)=30cm=` distance of load from the point of suspension
`:. W_(1)xx20cm=60 gwtxx30cm`
`:. W_(1)=(60 gwtxx30cm)/(20cm)=90 gwt`