posted by Anne .
Consider a swimmer who wants to swim directly across a river. If the speed of the current is 0.31 m/s and the swimmer's speed relative to the water is 0.57 m/s, how long will it take her to cross a river that is 13 m wide?
vave = (change of displacement)/(time elapsed)
t = (change of displacement)/(average velocity)
t = (13 meters)/(0.57 m/s) = 22.8 s