Question

In which one of the following cases will the liquid flow in a pipe be most streamlined

• A. Liquid of high viscosity and high density flowing through a pipe of small radius
• B. Liquid of high viscosity and low density flowing through a pipe of small radius
• C. Liquid of low viscosity and low density flowing through a pipe of large radius
• D. Liquid of low viscosity and high density flowing through a pipe of large radius

Answer 1

Answer: (B)

Liquid of high viscosity and low density flowing through

a pipe of small radius

Answer 2

For streamline flow Reynold's number $N_{R} \propto \frac{r\rho}{\eta}$ should be

less. For less value of $N_{R}$, radius and density should be small

and viscosity should be high.