# Understanding frequency calculations of an object (e.g human body)

• Nathan M
In summary, the frequency of the human body can be calculated using Weins law, but this has nothing to do with resonances. The tissue vibrational frequency is not related to atomic properties and depends on factors such as stiffness, density, and shape at large scales. Most structures have multiple resonant frequencies, and the idea of there being only one resonance is oversimplified.
Nathan M
Apologies for the noob question.

The frequency of the human body can be calculated based on weins law as follows:

Wavelength = 0.002898/310 = 0.00000934838 m

Plugging this into the equation λν = c we get

frequency = 299792458 / 0.00000934838 = 32069 Ghz

Elsewhere, I see that the resonant frequencies of the human body (e.g the ocular cavity) are at around 20 Hz. I assume this is physical vibrational frequencies (and I even see papers on the fact that infra sound could cause undesirable effects). I am having some trouble reconciling these two notions of frequencies. The frequency is a result of the vibrations of the atoms (apologies for the oversimplification) so should there not be just one frequency per object. If the atoms of a cell vibrate at a particular frequency in order to generate the propagating field, should there not be just one frequency? How could there be two different frequencies for a particular cell?

Also, am I right in assuming that resonance could occur at both frequencies.

There is no "resonant frequency of a human body". You'll only find this in pseudoscience.

What you calculated is the rough frequency where things at room temperature (for this purpose, humans are at room temperature) emit most thermal radiation. This has nothing to do with resonances.
Nathan M said:
If the atoms of a cell vibrate at a particular frequency in order to generate the propagating field
There is no such thing happening.

weirdoguy
Apologies to @mfb. I was working on a reply and still wanted to post it.
Nathan M said:
The frequency is a result of the vibrations of the atoms (apologies for the oversimplification) so should there not be just one frequency per object.
This is not correct. The tissue vibrational frequency has very little to do with any vibrational frequency of the atoms. Acoustic resonance takes place with wavelengths that are many orders of magnitude larger than atoms. It depends on tissue stiffness, density, and shape at large scales, not atomic properties.

Consider for example water at its triple point. The atoms of the liquid, solid, and gas phases all are the same material and have the same frequency black body radiation corresponding to atomic-level vibrations and other thermal motions. But they all have different mechanical vibrations based on their differing stiffness and density and more importantly their macroscopic shape. The two types of frequencies are largely unrelated.

As another example, consider two strings of the same material and at the same temperature but at different lengths. The thermal vibrations are identical as are all atomic and molecular properties. However, because of the different macroscopic shape (length) the principle resonance frequency is different between the two.

Nathan M said:
How could there be two different frequencies for a particular cell?
Speaking strictly of mechanical resonance. The idea that there is only one resonant frequency of some mechanical structure. Is a huge oversimplification. Most structures have many resonant frequencies. For example many will have multiple resonances in bending and some resonances in torsion and maybe some in compression. Speaking purely of mechanical waves the idea that there is only one resonance is wrong. One resonance may be the strongest, but there are usually several. Great care must be taken to produce a structure like a tuning fork that has a nice clean single resonance. And even then it probably has other resonances, they are just outside the audible range.

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sophiecentaur

## 1. How is frequency calculated for an object?

The frequency of an object is calculated by dividing the number of cycles or repetitions of a specific action or movement by the total time it takes to complete those cycles. This is typically measured in hertz (Hz), which represents the number of cycles per second.

## 2. What factors can affect the frequency of an object?

The frequency of an object can be affected by several factors, including the mass, length, and stiffness of the object, as well as external forces such as gravity or friction. Additionally, the frequency can also be influenced by the object's environment, such as temperature or air resistance.

## 3. How does frequency relate to the human body?

In the human body, frequency is often used to measure the rate of a specific biological process or movement, such as heartbeats or breathing. It can also be used to analyze the vibration of tissues or organs, which can provide valuable information for diagnosing certain medical conditions.

## 4. Can frequency calculations be used to predict future movements of an object?

Frequency calculations can be used to make predictions about the future movements of an object, but they are not always accurate. This is because external factors and changes in the object's environment can affect its frequency, making it difficult to predict with complete certainty.

## 5. How can understanding frequency calculations be useful in everyday life?

Understanding frequency calculations can be useful in everyday life in many ways. For example, it can help us understand the mechanics of musical instruments and how different frequencies produce different sounds. It can also be used in engineering and design to create more efficient and stable structures, as well as in medicine for diagnosing and treating various health conditions.