Q132 / 180 · JIPMER 2019 · Physics

Two objects of mass $m$ each moving with speed $\mathrm{u~m} / \mathrm{s}$ collide at $90^{\circ}$, then final momentum is (assume collision is inelastic)

  • A
    $m u$
  • B
    $2 m u$
  • Correct answer
    C
    $\sqrt{2} m u$
  • D
    $2 \sqrt{2} \mathrm{mu}$

Solution

Speed of objects $=4 \mathrm{~m} / \mathrm{s}$ Since, both objects collide with $90^{\circ}$. Hence, by the law of conservation of momentum, Total moment before collision $=$ total momentum after collision $\begin{aligned} \mid \mathrm{muî}+\mathrm{mu \hat {j } |} & =\mathrm{P}_{\mathrm{f}} \\ \sqrt{\mathrm{m}^2 \mathrm{u}^2+\mathrm{m}^2 \mathrm{u}^2} & =\mathrm{P}_{\mathrm{f}} \\ \Rightarrow \quad \mathrm{P}_{\mathrm{f}} & =\sqrt{2} \mathrm{mu} \end{aligned}$

Hence, the correct answer is option: 'C'.

Relevant Questions