$A$ spherical solid ball of volume $V$ is made of a material of density $\rho_1$. It is falling through a liquid of density $\rho_2$ $(\rho_2 < \rho_1)$. Assume that the liquid applies a viscous force on the ball that is proportional to the square of its speed $v$,i.e.,$F_{viscous} = -kv^2$ $(k > 0)$. The terminal speed of the ball is:

$A$ small drop of water falls from rest through a large height $h$ in air; the final velocity is

What is the terminal velocity of a rain drop of radius $0.02 \ mm$ (in $cm \ s^{-1}$)? [Note that the coefficient of viscosity of air is $1.8 \times 10^{-5} \ N \ s \ m^{-2}$,density of water is $1000 \ kg \ m^{-3}$. Use $g = 10 \ m \ s^{-2}$ and density of air can be neglected in comparison with the density of water.]

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $A$ spherical body of radius $(5 \pm 0.1) \ mm$ having a particular density is falling through a liquid of constant density. The percentage error in the calculation of its terminal velocity is $4\,\%$.
Reason $R$: The terminal velocity of the spherical body falling through the liquid is inversely proportional to its radius.
In the light of the above statements,choose the correct answer from the options given below:

An air bubble of radius $1 \ cm$ rises from the bottom portion through a liquid of density $1.5 \ g/cc$ at a constant speed of $0.25 \ cm \ s^{-1}$. If the density of air is neglected,the coefficient of viscosity of the liquid is approximately,(in $Pa \ s$):

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