Problem: The lower end of a long plastic straw is immersed below the surface of the water in a plastic cup. An average person sucking on the upper end of the straw can pull water into the straw to a vertical height of 1.1 m above the surface of the water in the cup. What is the lowest gauge pressure that the average person can achieve inside his lungs?

FREE Expert Solution

Gauge pressure is given by:

$\overline{){\mathbf{P}}{\mathbf{=}}{\mathbf{\rho }}{\mathbf{g}}{\mathbf{h}}}$, where ρ is the density of water, g is the acceleration due to gravity, and h is the vertical height.

Lowest pressure achievable inside the lungs:

$\overline{){{\mathbf{P}}}_{\mathbf{l}\mathbf{u}\mathbf{n}\mathbf{g}\mathbf{s}}{\mathbf{=}}{{\mathbf{P}}}_{{\mathbf{0}}}{\mathbf{+}}{\mathbf{P}}}$, where P0 is atmospheric pressure.

Problem Details

The lower end of a long plastic straw is immersed below the surface of the water in a plastic cup. An average person sucking on the upper end of the straw can pull water into the straw to a vertical height of 1.1 m above the surface of the water in the cup. What is the lowest gauge pressure that the average person can achieve inside his lungs?