A man can swim with a speed of `4kmh^(-1)` in still water. He crosses a river 1km wide that flows steadly at `3kmh^(-1)`. If he makes his strokes normal to the river current, how far down the river does he go when he reaches the other bank?

Explanation

Here, `vecV_(m)` = `4 km h^(-1), vec_(v_(r)) = 3kmh^(-1)`,
OA=1km
let t = time taken by man to reach the other bank.
then, `t=(OA)/(v_(m))= 1/4 = 0.25h`
Distance, AB= `v_(r) xx t= 3 xx (0.25)= 0.75 km`