Breathing is cyclic and a full respiratory cycle from the beginning of inhalation to the end of exhalation takes about 5 s. The maximum rate of air flow into the lungs is about 0.5 This explains, in part, why the function
has often been used to model the rate of air flow into the lungs. If inhalation occurs during the interval 0 what is the average rate of air flow during inhalation?
