A boy weighing 50 kg jumped from a resting boat to the shore. The boy’s speed is 4 ms. What is the mass of the boat

A boy weighing 50 kg jumped from a resting boat to the shore. The boy’s speed is 4 ms. What is the mass of the boat if it acquired a speed of 1 ms?

Given:
mm = 50 kg
Vm = 4m / s
Vl = 1m / s
ml =?
Decision:
Let’s write the law of conservation of momentum:
mmVm-mlVl = 0 // speeds of the boat and the boy are oppositely directed, hence the minus
// on the right – the sum of impulses before the boy’s jump (the bodies were at rest), on the left – after
mlVl = mmVm
ml = mmVm / Vl
ml = 50 * 4/1 = 200kg
Answer: 200 kg