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A hunter wishes to cross a river that is 1.5 km wide and flows with a speed of 5.0km/h parallel to its banks. the hunter uses a small powerboat that moves at a maximum speed of 12 km/h with respect to the water. What is the minimum time necessary for crossing?

3. The Attempt at a Solution

5km/h^2 + 12Km/h^2=sq rt 169km/h^2 = 13 km/h

The hunter moves really moves at 13 km/h to the right because of the water moving upstream. 13 is the vector resultant of 5 north and 12 east.

So, T=D/V

T=width of stream/velocity of hunter

T=1.5km/12km/h = 0.125 h