Question

Two particles of masses $1\text{kg}$ and $2\text{kg}$ are located at $x=$$0\text{m}$ and $x=3\text{m}$. The position of their centre of mass (with respect to mass $1\text{kg}$) is

• A. $1\text{m}$
• B. $2\text{m}$
• C. $2.2\text{m}$
• D. $2.4\text{m}$

Answer 1

The correct option is B $2\text{m}$

Here, $m_1$ is taken as reference, so $x_1=0$
$x_2$ = distance of $m_2$ from $m_1=3\text{m}$
$\therefore$ Position of centre of mass, $x_{\text{com}}=\frac{m_1{x}_1+m_2{x}_2}{m_1+m_2}$ from $m_1$
$=\frac{1\times 0+2\times 3}{1+2}$
$=\frac{6}{3}=2\text{m}$ from $m_1$