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A 50 kg boy jumps off the back of a 4 kg skateboard. At the start, the boy and board are moving together at 5 m/s. The boy’s velocity after the jump has been reduced to 2.5 m/s, but in the same direction. Calculate the skateboard’s velocity immediately after the boy jumps

Respuesta :

Answer:

36.25 m/s.

Step-by-step explanation:

The momentum of the board and the boy  after the boy jumps is  the same as the momentum when the boy was on the board. ( Conservation of Momentum Law).

Momentum = mass * velocity.

So  MV (the momentum before the jump) = 54 * 5 = 270 kg m/s.

After it is 50 * 2.5 + 4V   where V = velocity of the board immediately after the jump.

270 = 125 + 4V

4V = 145

V = 36.25 m/s.

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