A man can swim with a speed of 4.0 km/h in still water. How long does he take tocross a river 1.0 km wide if the river flows steadily at 3.0 km/h and he makes hisstrokes normal to the river current? How far down the river does he go when he reaches the other bank ?
Given: The speed of man in still water is 4.0 kmh − 1 , width of the river is 1.0 km and the speed of river flow is 3.0 kmh -1 .
Time taken by man to cross the river is given as,
t = w v m
Where, v m is the speed of man in still water and w is the width of river.
By substituting the given values in the above expression, we get
t = 1 4 hours = 15 minutes
Distance covered with flow of the river is given as
d = v r × t
Where, v r is the speed of river flow.
By substituting the given values in the above expression, we get
d = 3 × 1 4 = 3 4 km = 750 m
Thus, the river goes 750 m when he reaches the other bank.
Given: The speed of man in still water is
Time taken by man to cross the river is given as,
Where,
By substituting the given values in the above expression, we get
Distance covered with flow of the river is given as
Where,
By substituting the given values in the above expression, we get
Thus, the river goes
