Question

A swimmer, capable of swimming at a speed of 1.0 m/s in still water (i.e., the swimmer can swim with a speed of 1.0 m/s relative to the water), starts to swim directly across a 3.0-km-wide river. However, the current is 0.91 m/s, and it carries the swimmer downstream.

(a) How long does it take the swimmer to cross the river?
(b) How far downstream will the swimmer be upon reaching the other side of the river?

Answer 1

A: Since it's just asking how long it takes to cross the river, the velocity of the water does not matter since it's perpendicular to the swimmer's path.

d / v = t

3000 m / 1.0 m/s = 3000 s

B:

t * v = d

3000 s * 0.91 m/s = 2730 m