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
$\frac{{Vg\left( {{\rho _1} - {\rho _2}} \right)}}{k}$
$\sqrt {\;\frac{{Vg\left( {{\rho _1} - {\rho _2}} \right)}}{k}} $
$\;\frac{{Vg{\rho _1}}}{k}$
$\;\sqrt {\frac{{Vg{\rho _1}}}{k}} $
A sphere is dropped under gravity through a fluid of viscosity $\eta$ . If the average acceleration is half of the initial acceleration, the time to attain the terminal velocity is ($\rho$ = density of sphere ; $r$ = radius)
Which falls faster, big rain drops or small rain drops ?
In an experiment to verify Stokes law, a small spherical ball of radius $r$ and density $\rho$ falls under gravity through a distance $h$ in air before entering a tank of water. If the terminal velocity of the ball inside water is same as its velocity just before entering the water surface, then the value of $h$ is proportional to :
(ignore viscosity of air)
$1$ poiseille $=$ .......... poise
When a body falls in air, the resistance of air depends to a great extent on the shape of the body, $ 3 $ different shapes are given. Identify the combination of air resistances which truly represents the physical situation. (The cross sectional areas are the same).