Question

The following problem is adapted from Tinoco, et al., Physical Chemistry: Principles and Applications in Biological Sciences, 4th edition: Every time a human being breathes out, he or she pushes out about 0.5 L of gas against a pressure of about 1 bar (assuming a pressure at sea level).

a. What amount of work (in J) is done in each breath out? Report your answer to two significant figures.

b. Estimate how many breaths you take in a 24 hour day and then calculate the total amount of work you do in exhaling over the course of one day.

c. The height of Grandfather Mountain in western North Carolina is 1812 m. Remembering that the energy needed to lift a mass m through a height h is equal to mgh, where g is the acceleration due to gravity, estimate the mass m that could be lifted to the peak of Grandfather Mountain using the same amount of work that you do in exhaling in one day. (Optional extension: Do the calculation taking into account that the pressure at the top of Grandfather Mountain is less than that at sea level. Hints: Do you do or more less work in each breath out? How does that affect the mass you can lift? What is the dependence of pressure on height above sea level?)

Answer 1