Biomechanics is an area of study
wherein knowledge and methods of mechanics are applied to the structure and
function of the living human system. Period is a biomechanical term that refers
to the amount of time required for an object to complete single cycle of motion.
A phenomenon is periodic when it reproduces, identical to itself, at the end of a certain time called period.
A periodic phenomenon is a phenomenon that is reproduced, identical to itself, at equal time intervals. An example of periodic movement in biology in the heart rhythm: even if a physical activity can modify their rhythm, the heart beats represent a good example of periodic phenomenon.
The placebo pills in your birth control pack have no hormones in them, but you are still protected from pregnancy during this seven-day break as long as you took the first 21 pills correctly