Question

An observer standing near the shore notes that Ram is swimming upstream at 0.9 m/s and Shyam is
swimming downstream at 1.5 m/s. If velocity of both in still water is the same woat is velocity of river?
(A) 0.1 m/s
(B) 0.2 m/s
(C)0.3 m/s
(D)0.4 m/s​

Answer 1

Dear Sarthak,

◆ Answer -

(c) Velocity of the river = 0.3 m/s

◆ Explaination -

Let vm be the velocity of Ram / Shyam in still water and vr be velocity of river.

Velocity of Ram swimming upstream is given by -

vu = vm - vr

0.9 = vm - vr ...(1)

Velocity of Shyam swimming downstream is given by -

vd = vm + vr

1.5 = vm + vr ...(2)

Equation (2) - Equation (1)

1.5 - 0.9 = (vm + vr) - (vm - vr)

0.6 = vr + vr

vr = 0.6 / 2

vr = 0.3 m/s

Therefore, velocity of the river stream is 0.3 m/s.

Thanks dear. Hope that helps.