Question

A particle of mass $m$ moving with speed $v$ towards east strikes another particle of same mass moving with same speed $v$ towards the north. After striking, the two particle fuse together. Determine the 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. $v\sqrt{2}$

Answer 1

The correct option is C $\frac{v}{\sqrt{2}}$

Moment before and after collision is same.

$2m\overrightarrow{u}=mv\hat{1}+mv\hat{j}2\overrightarrow{u}=v\hat{1}+v\hat{j}|\overrightarrow{v}=|\frac{1}{2}\sqrt{v^2+v^2}=\frac{v}{\sqrt{2}}$