Question

The flow rate of water from a tap of diameter 1.25 cm is 3 L per min. The coefficient of viscosity of water is ${10}^{-3}$ Pa s. The nature of the flow is

• A. Unsteady
• B. Turbulent
• C. Laminar
• D. None of these

Answer 1

Answer: (B)

Turbulent

Here, diameter of the tap,

$D=1.25cm=1.25\times {10}^{-2}m$

Density of water, $\rho ={10}^{3}kg{m}^{-3}$

Coefficient of viscosity,$\eta ={10}^{-3}Pas$

Volume of water flowing out per second is

$Q=3Lpermin=\frac{3\times {10}^{-3}{m}^3}{60s}=5\times {10}^{-5}{m}^3{s}^{-1}$

Reynolds number is given by:

$R_e=\frac{4\rho Q}{\pi D\eta }=\frac{4\times {10}^{3}kg{m}^{-3}\times 5\times {10}^{-5}{m}^3{s}^{-1}}{3.14\times 1.25\times {10}^{-2}m\times {10}^{-3}Pas}$$=5095>2000$

Thus, the flow will be turbulent.