A metre scale is balanced on a knife edge at its centre. When two coins, each of mass 10   g are put…

A metre scale is balanced on a knife edge at its centre. When two coins, each of mass 10 g are put one on the top of the other at the 10.0 cm mark the scale is found to be balanced at 40.0 cm mark. The mass of the metre scale is found to be x×10-2 kg. The value of x is _____ .

Solution

Let the mass of the scale be m.

The centre of mass of the scale will be at 50 cm.

Applying torque balance, 

0=mg×50-40-2×10g×40-10⇒m=60 g=6×10-2 kg

Asked in: JEE Main 2022 (24 Jun Shift 1)

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