question_answer

A particle of mass m moving with velocity v colloids with a stationary particle of mass 2w. The speed of the system, after collision, will be

A) \[v/2\]    

B) \[2v\]                   

C) \[v/3\]                

D) \[3v\]

Correct Answer: C

Solution :

Here \[{{m}_{1}}=m\] \[{{m}_{2}}=2m\] \[{{v}_{1}}=v\] \[{{v}_{2}}=0\] Let the speed of the system after collison = v Using the principle of conservation of linear momentum \[{{m}_{1}}{{v}_{1}}+{{m}_{2}}{{v}_{2}}=({{m}_{1}}+{{m}_{2}})v\] \[\Rightarrow \] \[v=\frac{mv+2m\times 0}{m+2m}=\frac{mv}{3m}=\frac{v}{3}\]