Question

A uniform metre rule of mass $100g$ is balanced on a fulcrum at mark $40cm$ by suspending an unknown mass $m$ at the mark $20cm$. Find the value of $m$.

• A. $50kg$
• B. $5kg$
• C. $50g$
• D. $500g$

Answer 1

The correct option is C $50g$

As $100g$ is balanced at fulcrum it will have a perpendicular distance of $40cm$ from itself and mass $m$ will have $40-20=20cm$ distance.

Here moment of forces are equal that is balance each other.

Hence $m\times (40-20)=100\times (50-40)$
$\Rightarrow m=100/2=50g$.

Hence value of m is $50g$.