Question

Three masses are placed on the x-axis: $300g$ at origin, $500g$ at $x=40cm$ and $400g$ at $x=70cm$. The distance of the centre of mass from the origin is-

• A. $45cm$
• B. $50cm$
• C. $30cm$
• D. $40cm$

Answer 1

The correct option is D $40cm$

Let COM be at point $C$.

$\therefore X_{cm}=\frac{m_1{X}_1+m_2{X}_2+m_3{X}_3}{m_1+m_2+m_3}{X}_{cm}=\frac{300\times 0+500\times 40+400\times 70}{1200}=\frac{480}{12}{X}_{cm}=40cm$