A girl of mass 50 kg jumps out of a rowing boat of mass 300 kg on to the bank, with a horizontal velocity of 3 m/s. With what velocity does the boat begin to move backwards ?
The force F1 exerted by girl is the ‘action’ and the force F2 exerted by the boat is the ‘reaction’.
Now, momentum of the girl in one direction must be equal to the momentum of the boat in opposite direction.
m1 × v1 = m2 × v2
⇒ 50 × 3 = 300 × v2
⇒ v2 = 0.5
Hence, velocity with which the boat begins to move backwards is 0.5 m/s.
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