question_answer

A particle of mass m moving with speed v towards east strikes another particle of same mass moving with same speed v towards north. After striking, the two particles fuse together. With what speed this new particle of mass 2m will move in north-east direction?

A)  \[v\]                                    

B)  \[\frac{v}{2}\]

C) \[\frac{v}{\sqrt{2}}\]                                     

D)  \[v\sqrt{2}\]

Correct Answer: D

Solution :

                                                  From conservation of linear momentum                                 mv + mv = 2mv \[\sin {{135}^{o}}\]                                 \[2mv=2mv\,\times \frac{1}{\sqrt{2}}\]                                                 \[v=\sqrt{2}v\]