A river flows toward the east at 1.5 m/s. Steve can swim 2.2 m/s in still water. If he wishes to cross the river so that his direction is exactly northward, what direction relative to the water must he swim?
A) 55° north of west
B) 43° west of north
C) 34° north of west
D) 47° west of north

Question

Quizplus · Accepted Answer

Steve must aim upstream to counteract the river's eastward flow and maintain a northward direction. By using the Pythagorean theorem or trigonometry with the given speeds, the angle can be found using the arctan of the river's speed (1.5 m/s) over Steve's speed in still water (2.2 m/s), which gives an angle of approximately 43° west of north.

A River Flows Toward the East at 1