At rest, a man breathes 12 times a minute and each breath moves 500 mL…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
At rest, a man breathes times a minute and each breath moves mL. During hard exercise he breathes times a minute and each breath moves mL.
- How much air does he move in a minute at rest?
- How much air does he move in a minute during the exercise?
- How many times more air is this?
- For how long, in minutes, could the exercise air have lasted if he had moved at the resting rate?
Need a reminder? The key ideaShow
In inspiration the diaphragm and the external intercostal muscles contract, the volume of the chest rises and the pressure in the lungs falls below atmospheric pressure. In expiration they relax and the pressure rises slightly above atmospheric pressure. Air moved in a minute rate volume of each breath.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Rest: breaths a minute, mL each. Exercise: breaths a minute, mL each.
Plan. Find the air in a minute for each case, then divide.
Step 1. At rest. mL.
Step 2. Exercise. mL.
Step 3. Ratio. times.
Step 4. Part (d). The exercise air of one minute equals minutes at the resting rate.
Answer: mL; mL; times; minutes.
Check. Exercise raises both the rate and the size of each breath, so the air moved grows by more than either one alone.
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