4.13 A man can swim with a speed of 4.0 km/h in still water. How long does he take to cross a river 1.0 km wide if the river flows steadily at 3.0 km/h and he makes his strokes normal to the river current? How far down the river does he go when he reaches the other bank?
Speed of the man,vm=4km/h
Width of the river = 1 km
Time taken to cross the river = width of the riverspeed of the river = 14h = 14 × 60 = 15 min
Speed of the river,vr=3km/h
Distance covered with flow of the river=vr×t= 3 × 14 = 34 km
= 34 ×1000 = 750 m
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