4.12
Breathing is a cyclic process, with each full respiratory cycle lasting about 5 seconds.
The goal is to find the volume of inhaled air in the lungs at any time t during this cycle.
The rate of airflow changes over time and can be modeled using a sinusoidal function. It shows that airflow peaks during mid-inhalation and reverses during exhalation, with a maximum rate of about 0.5 L/s.
The infinitesimal volume dV over a small time dt accumulates to the total inhaled volume by integrating the airflow rate from 0 to t.
The substitution method simplifies the integral by setting the variable u as 2πx over 5. The differential dx is expressed in terms of du to match the new variable. The limits of integration also change to match the new variable, ranging from 0 to 2πt over 5.
The integral becomes a standard sine form, whose integral is negative cosine, evaluated using the limits of integration.
This gives the volume of inhaled air in liters as a function of time during the breathing cycle, reaching its maximum during inhalation.
This model includes both direction and rate of airflow, giving a clear view of respiratory volume over time.
The process of breathing involves the periodic intake and expulsion of air, known as the respiratory cycle, which typically lasts about five seconds.…
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