Water $\text{(density:}\;1000\;\text{kgm}^{-3})$ stored in a cylindrical drum of diameter $1\;\text{m}$ is emptied through a horizontal pipe of diameter $0.05\;\text{m}$. A pitot-static tube is placed inside the pipe facing the flow. At the time when the difference between the stagnation and static pressure measured by the pitot-static tube is $10\;\text{kPa}$, the rate of reduction in water level in the drum is,
- $\frac{1}{200\sqrt5}\text{ms}^{-1}$
- $\frac{1}{75\sqrt{10}}\text{ms}^{-1}$
- $\frac{1}{50\sqrt{10}}\text{ms}^{-1}$
- $\frac{1}{40\sqrt5}\text{ms}^{-1}$