Why do we use kelvin to measure heat?

[grayson]

This might seem like a crazy thread but hear my logic behind it. Heat/Temperature is measured in kelvin based on SI units. But I propose two different ways to measure heat. Number one, hertz. Hertz I think is my favorite way of measuring heat. The reason is that I love waves. Waves are an accurate way of measuring a lot of things, and you can even measure heat in it. From what I learned, heat, or thermodynamic energy, is just particles moving up and down a bunch of times (Or in other words, a simple harmonic oscillator). If heat is a S.H.O, then you should be able to measure its frequency. Moving on, we have joules. I am also a fan of energy and heat can be expressed as thermodynamic energy. So, if we can express heat as thermodynamic energy, we can measure it in joules. Also, before you say anything about Joules over Kelvin being a measurement of entropy, yes, I know about that, I just think we need a better way to measure thermodynamic energy. Anyways, that is my proposal for measuring thermodynamic energy.

[Genady]

"Why do we use kelvin to measure heat?"

We do not.

[exchemist]

19 minutes ago, grayson said:

This might seem like a crazy thread but hear my logic behind it. Heat/Temperature is measured in kelvin based on SI units. But I propose two different ways to measure heat. Number one, hertz. Hertz I think is my favorite way of measuring heat. The reason is that I love waves. Waves are an accurate way of measuring a lot of things, and you can even measure heat in it. From what I learned, heat, or thermodynamic energy, is just particles moving up and down a bunch of times (Or in other words, a simple harmonic oscillator). If heat is a S.H.O, then you should be able to measure its frequency. Moving on, we have joules. I am also a fan of energy and heat can be expressed as thermodynamic energy. So, if we can express heat as thermodynamic energy, we can measure it in joules. Also, before you say anything about Joules over Kelvin being a measurement of entropy, yes, I know about that, I just think we need a better way to measure thermodynamic energy. Anyways, that is my proposal for measuring thermodynamic energy.

It won’t work.

Firstly, thermal energy is divided between different degrees of freedom, only some of which are vibrations, the others being translations and rotations.

Secondly, where vibrations are involved, different substances have different characteristic frequencies of vibration. 

Temperature, on the other hand, is proportional to the total thermal kinetic energy of an object, regardless of what substance it consists of, or what physical state it is in. 

 

Edited January 7 by exchemist

[grayson]

26 minutes ago, Genady said:

"Why do we use kelvin to measure heat?"

We do not.

Well, you could have at least explained why we do not use kelvin.

14 minutes ago, exchemist said:

It won’t work.

Firstly, thermal energy is divided between different degrees of freedom, only some of which are vibrations, the others being translations and rotations.

Secondly, where vibrations are involved, different substances have different characteristic frequencies of vibration. 

Temperature, on the other hand, is proportional to the total thermal kinetic energy of an object, regardless of what substance it consists of, or what physical state it is in. 

 

This is a good explanation for why we do not use frequency for heat. My thought is proven wrong. +1

[sethoflagos]

57 minutes ago, exchemist said:

Temperature, on the other hand, is proportional to the total thermal kinetic energy of an object

To emphasise this point, the Kelvin was redefined in May 2019 as:

Quote

an absolute scale, which is defined such that 0 K is absolute zero and a change of thermodynamic temperature T by 1 kelvin corresponds to a change of thermal energy kT by 1.380649×10⁻²³ J. The Boltzmann constant k = 1.380649×10⁻²³ J⋅K⁻¹ was exactly defined in the 2019 redefinition of the SI base units such that the triple point of water is 273.16±0.0001 K.

... though perhaps the wikipedia article should clarify that it's strictly one degree of freedom of thermal energy change rather than the total change.

Edited January 7 by sethoflagos
Clarification

[Genady]

1 hour ago, grayson said:

you could have at least explained why we do not use kelvin

You did not ask.

[swansont]

2 hours ago, grayson said:

From what I learned, heat, or thermodynamic energy, is just particles moving up and down a bunch of times (Or in other words, a simple harmonic oscillator). If heat is a S.H.O, then you should be able to measure its frequency

Heat is energy transfer, owing to a temperature difference.

It is not particles moving up and down. If that were the case, why would energy be transferred between objects sitting next to each other, especially if they are not in contact? 

The motion of particles owing to the thermal content can have a frequency - the vibration of atoms in a solid, for example - but the frequencies of all the atoms are not the same, nor are they constant. In an ideal gas the motion is random, and the speeds follow a distribution. Pretty far from being a SHO.

1 hour ago, grayson said:

Well, you could have at least explained why we do not use kelvin.

Kelvin is used for temperature. It’s not an energy. As the link from sethoflagos points out, kT has units of energy

[iNow]

5 hours ago, grayson said:

you could have at least explained why we do not use kelvin.

Because we use it to measure temperature not heat 

X-posted

[falkor1995]

OP  i know this can be frustrating, but unfortunately our language is limited, so you cannot assume the word temperature=heat.   while they are proportional, that does not mean they are the same thing.    I would recommend going to libgenrus and getting a heat transfer book.    this will teach you about the transfer of energy and how entropy plays a role in this process.    dont feel like your stupid, this is not an intuitive thing

[Hanryq]

thank you! very interesting!