Question

Are human hearts, on an average, found to beat 75 times a minute. Calculate its frequency
(A) 1.25Hz
(B) 2.5Hz
(C) 7.5Hz
(D) 75Hz

Answer 1

In this question,we are going to apply the concept of frequency and it is defined as the number of oscillations per unit time and in SI unit it is the number of oscillations per second.

Complete step by step answer:
The heart beats at a rate of 75 beats per minute which itself is the frequency of the heartbeat, but we must calculate it in SI units.The SI unit of frequency is Hertz. One Hertz is defined as the number of oscillations in one second. We must calculate the heartbeat frequency per second.
Now we know: -
$1\min = 60\sec$
So, frequency of the heartbeat (f) is: -
$f = 75beats/\min$
$\Rightarrow f = \dfrac{{75beats}}{{1\min }}$
$\Rightarrow f = \dfrac{{75beats}}{{60\sec }}$
$\Rightarrow f = \dfrac{{75}}{{60}}Hz$
$\Rightarrow f = 1.25Hz$
Hence, option (A) is the correct answer.

Additional Information:
Here the frequency of the heartbeat is given as 75 beats per minute, but in real life heartbeats are involuntary. So, it is very difficult for any two beats to have the exact same timings since it is a natural phenomenon. The heartbeat frequencies are mostly as a fractional value and rarely it is observed as a whole number. Although it is mentioned in the question as 75 beats per minute, it may be 75.1 or 75.2 or maybe 74.9 or 74.8, anywhere between 74.5 to 75.5. Also, we cannot calculate the exact frequency of the heartbeats as mentioned above; it is not a natural phenomenon, so what we calculate is the average frequency of the heartbeat averaged over a large period.

Note: The frequency should be calculated in SI unit, therefore time should also be measured in its SI unit i.e. second and also remember that higher the frequency, lesser will be the time period of an oscillation.