A boy jumped horizontally from the bow of the boat, moving by the lake at a speed of 3 m / s, at a speed of 6 m / s relative

A boy jumped horizontally from the bow of the boat, moving by the lake at a speed of 3 m / s, at a speed of 6 m / s relative to the boat in the direction opposite to the movement of the boat. The boy’s weight is 50 kg, the boat’s weight is 200 kg. Calculate the speed of the boat immediately after the boy’s jump.

Given: V = 3 m / s
v = 6m / s
M = 200 kg
m = 50 kg
Find: V ’-?
Decision:
(M + m) * V = MV ’+ mv
V ‘= (M + m) * V – mv / M
V ‘= V + (V-v) * m / M
V ‘= 3 m / s + (3 m / s – 6 m / s) * 50 kg / 200 kg = 0.25 m / s
Answer: the speed of the boat after the boy’s jump will be 0.25 m / s