Se trata de suma algebraica de vectores
a) canoa___________> vc 1,5 m/s
rio _____________________> vr 2,0 m/s
___________________________________> vc + vr = 1,5 + 2,0 = 3,5 m/s
b) canoa___________________________> vc 3,0 m/s
rio ________________< vr 2,0 m/s
_____________> vc - vr = 3,0 - 2,0 = 1,0 m/s