Along-distance swimmer is able to swim through still water at 4.0 km/h. she wishes to try to swim from port angeles, washington, directly north to victoria, british columbia, a distance of 50 km. an ocean current flows through the strait of juan de fuca from west to east at 3.0 km/h. in what direction (relative to north) should she swim to make the crossing along a straight line between the two cities?

Let be the direction the swimmer must swim relative to east. Then her velocity relative to the water is

The current has velocity vector (relative to the Earth)

The swimmer's resultant velocity (her velocity relative to the Earth) is then

We want the resultant vector to be pointing straight north, which means its horizontal component must be 0:

which is approximately 41º west of north.

explanation:

v=uf/(u-f)

= 5.-10/(5+10) convex lens has negative focal length

answer: 31, 5556. 952 seconds