A rower whose speed of rowing is u crosses a river of width s to a point exactly opposite. Find the time of the journey if the speed of the stream is V( less than u)

Answer 1

at time t, we must have

s^2 + (vt)^2 = (ut)^2
(u^2 - v^2)t^2 = s^2
t = s/√(u^2-v^2)