Question

The heart of a man beats $75$ times a minute. What is its frequency?
A) $1.25\,{s^{ - 1}}$
B) $2.5\,{s^{ - 1}}$
C) $7.5\,{s^{ - 1}}$
D) $75\,{s^{ - 1}}$

Answer 1

Here we have to apply the concepts of time period and frequency.
Time period refers to the time it takes for something to happen. Frequency is the quantity of the rate. Period is a quantity of time. Frequency is a period per second. Period is the seconds of the cycle.
Frequency occurs at regular intervals of time period.

Complete step by step solution:
In sinusoidal wave motion, as seen above, the particles travel about the mean or mean location with the passage of time. Particles climb until they reach the highest point, which is the crest, and then begin to sink until they reach the lowest point, which is the trough.

The loop is repeated in a uniform sequence. The time period of wave oscillation is known as the time taken by any part of the string to complete one of those oscillations.

How long the time span is will depend on the event you want to calculate the frequency for-something that occurs very rapidly or very frequently will be calculated over a brief period of time (seconds or minutes) when very slow or very unusual events can need to be calculated over a number of years, decades or more.

The frequency of a sinusoidal wave can be defined as the number of complete oscillations made by any wave variable per unit time.
$f = \dfrac{1}{T}$

We need to estimate the time in seconds to determine the frequency in hertz.
That is, $1$ minute $= 60$ seconds.
The number of times it beats $= 75$ times a minute.
Frequency has been given as,
Number of times beats over total time taken in seconds
$= \dfrac{{75}}{{60}} = 1.25\,{s^{ - 1}}$

Thus, the frequency of a man's pulse is $1.25$ times per second.

Hence option A is the correct answer.

Note:
Here we have to convert the minute to seconds. Also, we have to remember that frequency is the inverse of time period and vice versa.