b
સળીયા ની લંબાઈ \( = \,\,\left| {{{{{\vec r}}}_{\text{2}}}\, - \,\,{{\vec r}_1}} \right|\,\, = \,\,\sqrt {{{(4\,\, - \,\,2)}^2}\, + \,\,{{(2\,\, - \,\,5)}^2}} \,\, = \,\,\sqrt {13} \,\,m\)

દ્રવ્યમાન કેન્દ્ર \({{{{\vec r}}}_{{\text{CM}}}}\, = \,\,\frac{{{m_1}{{\vec r}_1}\, + \,\,{m_2}{{\vec r}_2}}}{{{m_1}\, + \,\,{m_2}}}\,\, = \,\,\frac{3}{5}\,\,(2\,\hat i\,\, + \,\,5\,\hat j)\,\, + \,\,\frac{2}{5}\,(4\,\hat i\,\, + \,\,2\,\hat j)\,\)

\(\, = \,\,\left( {\frac{{14}}{5}\,\hat i\,\, + \,\,\frac{{19}}{5}\,\hat j} \right)\,m\)