Question

Particles A and B of masses 20 gm and 40 gm are simultaneously projected at angles ${45}^0$ and ${135}^0$ from two points P and Q with a velocity 49m/s each. They collide in their path, after collision if A retraces its path, velocity of B is

• A. 49 m/s
• B. 24. 5 m/s
• C. zero
• D. 98 m/s

Answer 1

The correct option is C zero

Since the word retrace is given so both particles must be at highest point of their trajectory.
Using momentum conservation
$40\times \frac{49}{\sqrt{2}}-20\times \frac{49}{\sqrt{2}}=20\times \frac{49}{\sqrt{2}}+v\times 40$
$v=0$