here we can say that there is no external force on fisherman and dock
so here we will use momentum conservation theory
As per momentum conservation
initial momentum of fisherman + boat = final momentum of fisherman + boat

now we will have



so the speed of boat and fisherman will be 1.16 m/s
No
For example a rock was broken into one big and one little piece. The properties of these 2 pieces are still the same even though they have different shapes.