1)

 In the system of two particles of masses m1 and m2, the first particle is moved by a distance d towards the centre of mass.To keep the centre of mass unchanged, the second  particle will have  to be moved by a distance


A) $\frac{m_{2}}{m_{1}}d,$ towards the centre of mass

B) $\frac{m_{1}}{m_{2}}d,$ away fron the centre of mass

C) $\frac{m_{1}}{m_{2}}d,$ towards the centre of mass

D) $\frac{m_{2}}{m_{1}}d,$ away from the centre of mass

Answer:

Option C

Explanation:

 Lert x1  and x2  be the position of masses m1  and m2, respectively 

 The position of centre of mass is 

$X_{CM}$=$\frac{x_{1}m_{1}+x_{2}m_{2}}{m_{1}+m_{2}}$

 If  $\triangle x_{1}$ and $\triangle x_{2}$  be the changes in positions , then change in the position  of the  centre of mass,

$\triangle X_{CM}=\frac{\triangle x_{1}m_{1}+\triangle x_{2}m_{2}}{m_{1}+m_{2}}$

 Given that  , the centre of mass remains unchannged  i.e, $\triangle$XCM =0 and  $\triangle x_{1}$ =d

 $\Rightarrow 0=\frac{dm_{1}+m_{2}\triangle x_{2}}{m_{1}+m_{2}}$

 or    $\triangle x_{2}=-\frac{m_{1}}{m_{2}} d$