A boy of mass 50kg is standing on a frictionless surface. He throws a ball of mass 2kg away from him with a speed of 10m/s. Find the final speed of the centre of mass.
The question was asked in exam.
Question is from System of Particles topic in section System of Particles and Rotational Motion of Physics – Class 11
Select the correct answer from above options
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Correct choice is (a) 0m/s
The best explanation: Initially the boy was at rest and there is no friction, so the net force on the ball-boy system is zero. Hence, their momentum change will be zero and final velocity of centre will also be zero. Note that boy will move backwards with a speed of 2*10/50 = 0.4m/s.