Two balls of masses \(60 g\) and \(40 g\) respectively, are attached firmly to the ends of a light metre rule. The centre of gravity of the system is
A. \(60 cm\) from the heavier mass B. at the mid-point of the metre rule C. \(40 cm\) from the lighter mass D. \(40 cm\) from the heavier mass
Correct Answer: D
Explanation
taking moment about the pivot \(O\) $$ \begin{aligned} &40(x)=60(100-x) \\ &40 x=6000-60 x \\ &100 x=6000 \\ &x=\frac{6000}{100} \\ &x=60 cm \end{aligned} $$ \(60 cm\) from the lighter mass or \(40 cm\) from the heavier mass
