A ship P initially has position vector (-3i-2j)km relative to a port at O and moves with velocity (2i+4j)kmh
a. What is its position vector after i.) 2 hours ii.) t hours
b.) When is the ship due west of the port ?
Now I understand the first part but all they have said for b is its due west of the port when j = 0 an figured t=1/2 I dont understand how they have come to this conclusion what j has to do with being west overall im just confused if someone could please explain b this would be so helpful ! thankss