Which of the following quantities has the dimensions of $\frac{\pi P r^4}{8 Q l}$? (Where $P =$ pressure,$r =$ radius,$Q =$ volume flow rate in $m^3/s$,and $l =$ length.)

When a liquid of density $\rho$ flows through a tube of diameter $d$ with critical velocity $V$,then the Reynolds number is (where $\eta$ is the coefficient of viscosity of the liquid).

When a liquid flows through a tube,the Reynolds number is $900$. The flow of the liquid is:

Two liquids of densities $d_1$ and $d_2$ are flowing in identical capillary tubes under the same pressure difference. If $t_1$ and $t_2$ are the times taken for the flow of equal quantities (mass) of liquids,then the ratio of the coefficient of viscosity of the liquids must be:

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.