# What speed will a stationary boat acquire when a person weighing 50 kg jumps onto

What speed will a stationary boat acquire when a person weighing 50 kg jumps onto the shore at a speed of 8 m / s directed horizontally if the boat’s mass is 200 kg?

mh = 50 kg.
ml = 200 kg.
Vch = 8 m / s.
Vl -?
Let’s use the law of conservation of momentum: in a closed system, the total momentum of all bodies included in the system remains unchanged.
The momentum of a body P is the product of the body’s mass m by its velocity V.
Since the boat with the person was at rest, the impulse before the person disembarked is 0.
mh * Vh – ml * Vl = 0.
mh * Vh = ml * Vl.
Vl = mh * Vh / ml.
Vl = 50 kg * 8 m / s / 200 kg = 2 m / s.
Answer: the boat will start sailing in the opposite direction of the disembarkation of a person at a speed of Vl = 2 m / s.

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