In the case of a fluid flowing on a horizontal surface, the flow of the fluid becomes unsteady when the Reynolds number $(R_n)$ is:

$A$ glass tube of uniform cross-section is connected to a tap with a rubber tube. The tap is opened slowly. Initially, the flow of water in the tube is streamline. The speed of flow of water to convert it into a turbulent flow is (radius of tube $= 1 \,cm$, $\eta = 1 \times 10^{-3} \,Ns/m^2$, $R_{n} = 2500$, and density of water $\rho = 10^3 \,kg/m^3$) (in $m/s$)

If water flows with a velocity of $20 \,cm \,s^{-1}$ in a pipe of radius $2 \,cm$, then the flow is (The coefficient of viscosity of water is $10^{-3} \,kg \,m^{-1} \,s^{-1}$ and density of water is $10^3 \,kg \,m^{-3}$).

For which of the following Reynolds numbers is a flow considered streamlined (laminar)?

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

Two capillary tubes of same radius $r$ but of lengths $l_1$ and $l_2$ are fitted in parallel to the bottom of a vessel. The pressure head is $P$. What should be the length of a single tube of the same radius $r$ that can replace the two tubes so that the rate of flow is same as before?