For a person at rest, the velocity v (in liters per second) of airflow during a respiratory cycle (the time from the beginning of one breath to the beginning of the next) is modeled by v = 0.85 sin (πt/3), where t is the time (in seconds).
(a) Find the time for one full respiratory cycle.
(b) Find the number of cycles per minute.
(c) Sketch the graph of the velocity function. Use the graph to confirm your answer in part(a) by finding two times when new breaths begin. (Inhalation occurs when v > 0, and exhalation occurs when v < 0.)