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At rest, Dev takes 16 breaths a minute, with 0.5 L of air in each.
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, Dev takes breaths a minute, with L of air in each. While he cycles uphill, he takes breaths a minute, with L in each. (a) How much air does he breathe in a minute in each case? (b) How much more air does he breathe in a minute ride than in minutes of rest?
Need a reminder? The key ideaShow
Air passes through the nostrils, pharynx, larynx, trachea (held open by rings of cartilage), bronchi and bronchioles to the alveoli, where gases are exchanged with the blood. Breathing in, the ribs lift and the diaphragm flattens. Residual air stays in the lungs. Haemoglobin carries oxygen; most carbon dioxide travels dissolved in the plasma.
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.
Step 1. At rest. L in a minute.
Step 2. Cycling. L in a minute.
Step 3. In 40 minutes. Rest: L. Cycling: L.
Step 4. The difference. L.
Answer: (a) L and L in a minute. (b) L more air in the ride.
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