Question

Water rises to a height $h$ in a capillary at the surface of earth. On the surface of the moon the height of water column in the same capillary and in the same conditions will be:

• A. $6h$
• B. $1.6h$
• C. $h$
• D. Zero

Answer 1

The correct option is A $6h$

$h=\frac{2Tcos\theta }{r\rho g}$

This is the formula for the rise in a capillary, where the symbols have their usual meanings.

If $h$ and $g$ on $earth$ and $moon$ are $h_e$ and $g_e,$ and $h_m$ and $g_m,$ then we know that

$g_m=\frac{g_e}{6}$

$h_m=\frac{2Tcos\theta }{r\rho \left(\frac{g}{6}\right)}$

$h_m=\frac{6\times 2Tcos\theta }{r\rho g}$ $=6h$

Other parameters do not change on moon.