$1$ poiseuille $=$ .......... poise

$A$ solid steel ball of diameter $3.6 \ mm$ acquires a terminal velocity of $2.45 \times 10^{-2} \ m/s$ while falling under gravity through an oil of density $925 \ kg/m^3$. Take the density of steel as $7825 \ kg/m^3$ and $g$ as $9.8 \ m/s^2$. The viscosity of the oil in $SI$ units is:

Two spheres of equal masses but radii $r_1$ and $r_2$ are allowed to fall in a liquid of infinite column. The ratio of their terminal velocities is

$A$ water drop of radius $1\,\mu m$ falls in a situation where the effect of buoyant force is negligible. The coefficient of viscosity of air is $1.8 \times 10^{-5}\,Nsm^{-2}$ and its density is negligible as compared to that of water $10^{3}\,kgm^{-3}$. The terminal velocity of the water drop is . . . . . . $\times 10^{-6}\,ms^{-1}$. (Take acceleration due to gravity $= 10\,ms^{-2}$)

While determining the coefficient of viscosity of the given liquid,a spherical steel ball sinks by a distance $h=0.9 \,m$. The radius of the ball $r=\sqrt{3} \times 10^{-3} \,m$. The time taken by the ball to sink in three trials are tabulated as follows:

Trial No.	Time taken by the ball to fall by $h$ (in second)
$1$.	$2.75$
$2$.	$2.65$
$3$.	$2.70$

The difference between the densities of the steel ball and the liquid is $7000 \,kg \,m^{-3}$. If $g=10 \,ms^{-2}$,then the coefficient of viscosity of the given liquid at room temperature is

The terminal velocity of a sphere of radius $3 \ mm$ falling in a viscous liquid is $10 \ cm/s$. The terminal velocity of a ball of radius $6 \ mm$ of the same material falling in the same liquid will be $...... \ cm/s$.