The velocity of a small ball of mass $M$ and density $d_1$ when dropped in a container filled with glycerin becomes constant after some time. If the density of glycerin is $d_2$,the viscous force acting on the ball is ($g$ = acceleration due to gravity).

$A$ small metal sphere of mass $M$ and density $d_{1}$,when dropped in a jar filled with liquid,moves with terminal velocity after some time. The viscous force acting on the sphere is ($d_{2} =$ density of liquid,$g =$ gravitational acceleration).

The average mass of rain drops is $3.0 \times 10^{-5} \, kg$ and their average terminal velocity is $9 \, m/s$. Calculate the energy transferred by rain to each square metre of the surface at a place which receives $100 \, cm$ of rain in a year.

Two spherical rain drops reach the surface of the earth with terminal velocities having ratio $16: 9$. The ratio of their surface area is

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

$A$ water drop whose radius is $0.0015 \, mm$ is falling through the air. If the coefficient of viscosity of air is $1.8 \times 10^{-5} \, kg/(m \cdot s)$,then assuming the buoyancy force is negligible,the terminal velocity of the drop will be: