The terminal velocity of a small sphere of radius $a$ in a viscous liquid is proportional to

The velocity of a small ball of mass $0.3 \, g$ and density $8 \, g/cc$ when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is $1.3 \, g/cc$,then the value of the viscous force acting on the ball will be $x \times 10^{-4} \, N$. The value of $x$ is [use $g = 10 \, m/s^2$]. (in $.125$)

$A$ copper ball of radius $3.0 \,mm$ falls in an oil tank of viscosity $1 \,kg / ms$. Then, the terminal velocity of the copper ball will be (Density of oil $= 1.5 \times 10^3 \,kg / m^3$, Density of copper $= 9 \times 10^3 \,kg / m^3$ and $g = 10 \,m / s^2$.)

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

The terminal velocity of a small-sized spherical body of radius $r$ falling vertically in a viscous liquid is given by the proportionality:

If the terminal speed of a sphere $A$ [density $\rho_A = 7.5 \ kg \ m^{-3}$] is $0.4 \ ms^{-1}$ in a viscous liquid [density $\rho_L = 1.5 \ kg \ m^{-3}$],the terminal speed of sphere $B$ [density $\rho_B = 3 \ kg \ m^{-3}$] of the same size in the same liquid is: (in $ms^{-1}$)