Two equal drops are falling through air with a steady velocity of $5 \, cm/s$. If these two drops coalesce,then the new terminal velocity will be ......... $cm/s$.

Two solid spheres of radii $2 \ mm$ and $4 \ mm$ are tied to the two ends of a light string and released in a liquid of specific gravity $1.3$ and coefficient of viscosity $1 \ Pa \cdot s$. The string is just taut when the two spheres are completely submerged in the liquid. If the density of the materials of the two spheres is $2800 \ kg \cdot m^{-3}$,then the terminal velocity of the system of the spheres is (take $g = 10 \ m \cdot s^{-2}$):

$A$ steel ball of radius $6 \ mm$ has a terminal speed of $12 \ cm s^{-1}$ in a viscous liquid. What will be the terminal speed of a steel ball of radius $3 \ mm$ in the same liquid (in $cm s^{-1}$)?

$A$ small metal sphere of radius $a$ is falling with a velocity $v$ through a vertical column of a viscous liquid. If the coefficient of viscosity of the liquid is $\eta$, then the sphere encounters an opposing force of

The terminal velocity of a metallic ball of radius $6 \ mm$ in a viscous fluid is $20 \ cm/s$. The terminal velocity of another ball of same material and having radius $3 \ mm$ in the same fluid will be . . . . . . $cm/s$.

$A$ spherical object is falling under gravity through a viscous fluid. The sphere attains the terminal velocity when