Question

One end of a glass capillary tube with a radius $r=0.05$ $cm$ is immersed into water to a depth of $h=2cm$. What pressure is required to blow an air bubble out of the lower end of the tube:
$T=7\times {10}^{-2}N/m$ and $\rho ={10}^3$ kg/ $m^3$)

• A. 480 N/ $m^2$ 2
• B. 680 N/ $m^2$ 3
• C. 2003 N/ $m^2$ 4
• D. 820 N/ $m^2$

Answer 1

The correct option is C 2003 N/ $m^2$ 4

Pressure $\left(P\right)=pgh+\frac{2T}{r}$

$={10}^3\times 10\times 2+\frac{2\times 7\times {10}^{-2}}{0.05}$

$=20000+3$

$=20003N/m^2$

Hence, the answer is $20003N/m^2.$