$A$ $20 \ cm$ long capillary tube is dipped in water. The water rises up to $8 \ cm$. If the entire arrangement is put in a freely falling elevator,the length of the water column in the capillary will be ....... $cm$.

Two narrow tubes of diameters $d_1$ and $d_2$ are joined together to form a $U$-tube open at both ends. If the $U$-tube contains water,the difference in water levels in the limbs is ($T$ is the surface tension of water,the angle of contact is zero,the density of water is $\rho$,and $g$ is the acceleration due to gravity).

Why is moisture retained in the soil when a farm is ploughed?

$A$ capillary tube is immersed vertically in water and the height of the water column is $x$. When this arrangement is taken into a mine of depth $d$,the height of the water column is $y$. If $R$ is the radius of earth,the ratio $\frac{x}{y}$ is

Water rises to a height of $20 \ mm$ in a capillary tube. If the radius of the capillary tube is made $\frac{1}{3}rd$ of its previous value,what is the new height of the capillary rise (in $mm$)?

Two capillaries made of the same material have radii $r_1 = 1 \, mm$ and $r_2 = 2 \, mm$. If the rise of the liquid in the first capillary $(r_1 = 1 \, mm)$ is $30 \, cm$,then the rise in the other capillary will be ........ $cm$.