What is critical speed in the context of fluid flow?

What is the value of Reynolds number for streamline flow?

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?

If $R_e > 2000$,then which type of flow exists? Explain.

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:

In deriving Bernoulli's equation,we equated the work done on the fluid in the tube to its change in the potential and kinetic energy.
$(a)$ What is the largest average velocity of blood flow in an artery of diameter $2 \times 10^{-3} \;m$ if the flow must remain laminar?
$(b)$ Do the dissipative forces become more important as the fluid velocity increases? Discuss qualitatively.