Question

By sucking through a straw, a boy can reduce the pressure in his lungs to $750$mm of Hg (density=$13.6g/c{m}^3$. Using a straw, he can drink water from a maximum depth of :

• A. $13.6cm$
• B. $1.36cm$
• C. $0.136cm$
• D. $10cm$

Answer 1

Answer: (A)

$13.6cm$

Given= Pressure of lungs $=750mm$ of $Hg$

To find= Maximum depth of water be can drink

The pressure difference between the atmosphere & lungs of student

is $=760-750=10mm$ of $Hg$

i.e $\rho gh=10mm$ of $Hg=1cm$ of $Hg$

This pressure is used to drink water

$\rho gh=1cm$ of $Hg$

$1000\times g\times h=1\times 13.6\times {10}^3\times g$

$h=13.6cm$