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Question:

A particle of mass 'm' is moving with speed '2v' and collides with a mass '2m' moving with speed 'v' in the same direction. After collision, the first mass is stopped completely while the second one splits into two particles each of mass 'm', which move at an angle 45° with respect to the original direction. The speed of each of the moving particles will be?

v/(2√2)

2√2v

2v

v/2

Solution:

Correct option is B. 2√2v
Linear momentum conservation
m(2v) + 2m(v) = m × 0 + m v' × 2cos(45°)
2mv + 2mv = 2mv' (1/√2)
4mv = √2mv'
v' = 4mv / (m√2) = 2√2v