Question

Question #77972

Answer 1

Well, first of all, you can talk about frequency or period of regularly periodic phenomena, i.e., phenomena that repeat themselves at regular equal intervals.

Also, Frequency is the number of oscillations in 1 second (measured in Hertz). The Period is the time to complete 1 oscillation or cycle (measured in seconds).

Let say, the period or frequency of a pendulum (ideal) are always the same because the oscillation repeats itself regularly (ideally, forever). Your heartbeat is already more complicated because its frequency (or period) can vary depending upon your stress, fatigue, etc. In this case you still use 1 second or the number of pulses in 1 second but you may need to measure it at various times (and so change the values according to the conditions).

You choose 1 second as basic interval because it fits into other MKS units and it is good for everybody. If you say 3 Hz everybody understands that your phenomenon repeats 3 times in 1 second or that it takes 1/3 second to complete one cycle without even knowing the nature of your phenomenon. There is no need to talk about a maximum time interval because your phenomenon (periodic) should continue forever, and also repeating at regular intervals (all the same) there is no need of an average time.
Hope it helps.