Question

A swimmer jumps from a bridge over a canal and swims 1 kilometer stream up. After that first kilometer, he passes a floating cork. He continues swimming for half an hour and then turns around and swims back to the bridge. The swimmer and the cork arrive at the bridge at the same time. The swimmer has been swimming with constant speed. How fast does the water in the canal flow?

Answer 1

Speed of the swimmer = v

Speed of water in canal = u

Speed of swimmer upstream = v - u

Speed of swimmer downstream = v + u

Speed of cork = u

When swimmer came across the cork, swimmer's relative speed is (v - u + u) = v.

So, after 1/2 hr distance between them = v/2

While returning back, swimmer's relative speed is (v + u - u) = v

=> Time taken by the swimmer to catch the cork = (v/2)/v = 1/2 hr

=> Cork traveled 1 km in (1/2 + 1/2) = 1hr

=> Speed = 1km/hr

Answer 2

Answer:

therefore the ans is 1 kmph