A swimmer capable of swimming at a speed c in still water is swimming in a stream in which the current is u (which we assume to be less than c). Suppose the swimmer swims upstream a distance L and then returns downstream to the starting point. Find the time necessary to make the round trip, and compare it with the time to swim across the stream a distance L and return. FIGURE 2.5 Example 2.3. The motion of a swimmer as seen by observer 0 at rest on the bank of the stream. Observer O Einoves with the stream at speed 11. _ .. Li?" C C