A boy of mass 60 kg is standing over a platform of mass 40 kg placed over a smooth horizontal surface. e throwsa stone of mass 1 kg with velocity v = 10 m/s at an angle of 45 ° w.r.t ground. Find the displacement of the platform (with boy) on the horizontal surface when the stone lands on the ground.

Dear Sanchit

total mass of body and plateform = 100kg

 conservation of momentum in horizontal direction     100V + 1*10cos45 =0

                                                                               V=-1/10√2 m/sec 

 negative sign indicates in the reverse direction.

 time  of filght = 2*10 sin 45 /10

                    = √2

 so in this time plateform will move  = V*t

                                                    = 1/10√2 * √2

                                                    = .1 m answer

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