Physics

Problem

A swimmer can swim with speed

v

in still water. The river flows with speed

u

(where

v > u

). When the swimmer crosses the river in the minimum possible time, it takes

t_{1}

seconds. When she crosses the same river along the shortest possible path, it takes

t_{2}

seconds. Find the expression for the river width

w

in terms of

u

t_{1}

, and

t_{2}