A boy of mass 25 kg stands on a board of mass 10 kg which in turn is k

1.	A boy of mass 25 kg stands on a board of mass 10 kg which in turn is kept on a frictionless horizontalice surface. The boy makes a jump with a velocity component 5 m/s in horizontal direction with respectto the ice. With what velocity does the board recoil? With what rate are the boy and the board separatingfrom each other ?
Answer» Initial momentum of the system is 0 as , no one is moving Let the boy jumps with velocity 5 w.r.t ground and board moves with -V with respect to groud in opposite direction now, on conserving linear momentum 0 = 25(5) + 10(-V) => 10v = 255=> 10v = 25(5)=> V = 12.5 m/s and V relative of boy w.r.t board = 5-(-12.5) = 17.5 m/s

A boy of mass 25 kg stands on a board of mass 10 kg which in turn is kept on a frictionless horizontalice surface. The boy makes a jump with a velocity component 5 m/s in horizontal direction with respectto the ice. With what velocity does the board recoil? With what rate are the boy and the board separatingfrom each other ?

Answer»

Initial momentum of the system is 0 as , no one is moving

Let the boy jumps with velocity 5 w.r.t ground and board moves with -V with respect to groud in opposite direction

now, on conserving linear momentum

0 = 25*(5) + 10*(-V)

=> 10v = 25*5=> 10v = 25*(5)=> V = 12.5 m/s

and V relative of boy w.r.t board = 5-(-12.5) = 17.5 m/s

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