Question

Two objects moving with speed $u$ m/s collide at $90^{\circ}$ then final momentum is: (Assume collision is inelastic)

• A. $mu$
• B. $2\, mu$
• C. $\sqrt{2}\, mu$
• D. $2\sqrt{2}\, mu$

Answer 1

Answer: (C)

The linear momentum is conserved in both elastic and inelastic collisions.
$P_{initial}\, =\, P_{final}$
$P_{initial}\, =\,mu\hat{i}\,+\,mu\hat{j}$
$=m\sqrt{2}u\quad\quad\quad\quad\quad\left[\because \,\sqrt{\left(mu\right)^{2}+\left(mu\right)^{2}}=\sqrt{2}mu\right]$
$P_{final} \,=\,\sqrt{2}mu$