Question

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

• A. 10 cm
• B. 75 cm
• C. 13.6 cm
• D. 1.36 cm

Answer 1

The correct option is C 13.6 cm

Given Pressure in lungs, $P_{lungs}$ =750 mm of Hg

and atmospheric pressure $P_{atm}$ =760 mm of Hg

Now pressure difference $\Delta P=760-750$ =10 mm of Hg=1 cm of Hg

Now 1 cm of Hg=${\rho }_{water}gh$

$1{\rho }_{Hg}g={\rho }_{water}gh$

$13.6=h$

$h=13.6cm$

So option C is correct.

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