Question

A long capillary tube of radius r-=1 mm open at both ends is filled with water and placed vertically . What will be the height (in cm ) of the column of water left in the capillary in nearest integer ? The thickness of the capillary walls is negligible .(Surface tension of water is 72 dyne/cm and $g=1000cm/se{c}^2$) .

Answer 1

Height of rise in capillary $=\frac{20\cos \theta }{Pgr}$

for $\theta ={90}^0$

$\Rightarrow h=\frac{2\times 72\cos 90\times {10}^{-3}}{{10}^3\times 1000\times {10}^{-1}\times {10}^{-2}\times {10}^{-3}}\frac{N\times m^3\times s^2}{m\times kg\times n\times m}$

$=0.144m$

Hence, the answer is $14.4cm.$