Question

A particle of mass m moving with horizontal speed 6 m/sec. If m<<M then for one dimensional elastic collision, the speed of lighter particle after collision will be

• A. 2 m/sec in original direction
• B. 2 m/sec opposite to the original direction
• C. 4 m/sec opposite to the original direction
• D. 4 m/sec in original direction

Answer 1

Answer: (A)

2 m/sec in original direction

Answer 2

$v_{1} = \left( \frac{m_{1} - m_{2}}{m_{1} + m_{2}} \right)u_{1} + \frac{2m_{2}u_{2}}{m_{1} + m_{2}}$

Substituting m₁ = 0, $v_{1} = - u_{1} + 2u_{2}$

⇒ $v_{1} = - 6 + 2(4)$ $= 2m ⥂ / ⥂ s$

i.e. the lighter particle will move in original direction with the speed of 2 m/s.