Question

The velocity of upper layer of water in a river is \(36\ kmh^{–1}\). Shearing stress between horizontal layers of water is \(10^{–3} Nm^{–2}\). Depth of the river is ______ m. (Co-efficient of viscosity of water is \(10^{–2} Pa.s\))

Answer 1

Correct Answer: 100

We know that,
\(F = -ηA\frac {du}{dx}\)

\(10^{-3} = 10^{-2} \times \frac {10}{h}\)

\(h =\frac {10^{-1}}{10^{-3}}\)
\(h = 100\ m\)

So, the answer is \(100 \ m\).