Assumptions

Why practical people cannot relate to physics

Question:
Two children in a 90kg boat are drifting southward with a constant speed of 1.5 m s^-1. Each child has a mass of 50kg. What is the velocity of the boat immediately after one of the children falls of the read of the boat?

Politically correct answer:
Child who drops down into water continue in his state of motion, southwards of 1.5m s^-1. Since velocities of the child do not change before and after he jumps, there is no change in the velocity of the boat.

A questionable doubt:
A says: we have to presume newton's first law ma
A says: then we can say that the child speed is same as the boat
A says: is it?
B says: ok
B says: but in real life
B says: wont the child just
B says: drown and die or sth
A says: -_-
A says: u xiang xiang li a bit feng fu...
B says: what
B says: haha really what
B says: can you imagine
B says: like
B says: this child falls off
B says: where got swim same speed as the boat
B says: prob like struggle struggle then drown
B says: :s

Life is really full of assumptions. There are theories, but whether we can apply them, or even apply them well, is a whole different thing. But comparatively, there's no right or wrong, just some "seemingly better", and different ideologies work for different people.