Two identical drops of water are falling through air with steady velocity $V$. If the two drops coalesce to form a single drop,what is the new terminal velocity of the single drop?

What is the rate at which a trapped bubble of $2 \,mm$ diameter rises through a solution of density $13.6 \times 10^3 \,kg/m^3$ and coefficient of viscosity $1.5 \,cP$ (in $\,m/s$)? Assume the density of air is negligible and $g = 10 \,m/s^2$.

$A$ small sphere of radius $r$ falls from rest in a viscous liquid. As a result,heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity,is proportional to

In an experiment,a small steel ball falls through a liquid at a constant speed of $10\, cm/s$. If the steel ball is pulled upward with a force equal to twice its effective weight,how fast will it move upward? ......... $cm/s$

Why do rain drops not possess a velocity greater than a certain limit? Explain.

In Millikan's oil drop experiment, a charged drop falls with terminal velocity $V$. If an electric field $E$ is applied in a vertically upward direction, then it starts moving in an upward direction with terminal velocity $2V$. If the magnitude of the electric field is decreased to $E/2$, then the terminal velocity will become