Question

A metre scale is balanced on a knife-edge at its centre. When a mass of $10$ kg is kept at the $12$ cm mark, the scale is balanced at $45$ cm. What is the mass of the metre scale?

• A. $56g$
• B. $76g$
• C. $86g$
• D. $66g$

Answer 1

The correct option is D $66g$

let $m=$ mass concentrated at E.

Balancing torque about the point O,

from the given figure,

$10g(45-12)=mg(50-45)$

$10\times 33=m\times 5$

$m=66g$