Heat and Temperature

We all know what it's like to feel hot or cold. But what is hot? What is cold? What is heat? What does temperature really measure? Don't pretend like you haven't lost sleep over this. Well you don't have to fret any longer, Prof Dave will take you through the details.

Check out "Is This Wi-Fi Organic?", my book on disarming pseudoscience!

[professor_m_gibbons]

@3:03 - the transfer of heat energy will NOT always alter the temperature of a system, such as when a phase change is occurring at a constant pressure. Very common misconception, so watch out.

[morrainn]

man, , , this dude really be saving my grades. thank you professor jesus

[aliasanon]

Excellent short and simple explanation.

[pritchardsangai]

I love the explanations, thank you very much.

[jorostuff]

I love when he says: "Let's check comprehension." I LOVE IT!

[voltdragneel]

after 10 hours I have my chemistry test and I was reading thermodynamic when I see notification of your video lol and yhea you're videos are useful

[aedenthegreatyt]

Any hard science concept: *exists*
Dave: *Understandable, have a great day*

[xyrhdks]

i didn’t understand one single thing lmao, i guess i’m really dumb

[kedarparab]

Man you actually explained nicely and scientifically than other videos

[cbtaylor]

I have a question that has troubled me for some time (making the link between the atomic world to the macroscopic). What happens if we have a spaceship in outer space, and let’s say it’s a perfect vacuum (so no friction will occur). If we accelerate the spaceship, it now has higher velocity and so higher kinetic energy. You could say therefore it has higher temperature? After all the average kinetic energy of all the particles has increased? This doesn’t make sense though. Is temperature relative? Another similar problem, say if the earth sped up due to a gravitational force, does that mean our individual temperature increases, after all our kinetic energy has increased.

[howitzerm]

i just saw the intro and was instant subscribe push!

[retsepilemothepu]

My Physics improved from 50% on semester test 1 to 97% on semester test 2🎉🎉
Thank you sir, I have nothing to offer. I’ll thank you properly in the future.

[mohammadhafeezullah]

thanks for my completing the first question of my assignment

[vivianasierra]

thank you I needed this video for my end of the year test!!! :)

[AntboReVLt]

thank you professor Dave- heat transfer of energy molecules - collision and friction, which phase change according to temperature manipulation.

[aedenthegreatyt]

My Chem. Honors teacher had me watch this video for an assignment. I was not disappointed.

[SW-nxjz]

Omg your the best! Thermochemistry is so confusing to me but your making it alot easier. I can't say thank you enough for these quick video!

[alriktimo]

Can I say that any system has no need to transfer its energy to the other one in contact but as a natural consequence of action and reaction the energy gets distributed, eventually making the whole system reach equilibrium. Doesn't necessarily imply that energy is transferred from hot to cold and not from cold to hot it is just that the former does the transfer with a faster rate than the latter. Correct my intuition if I am wrong.

[subhashishbehera]

Sir you're explaining things really good

[IEleMenTIx]

1:20 faster moving particles with higher temperaure ... is correct for gasses and liquids, but not a sufficient expression and explanation for temperature changes in solids. One could misinterprete the statement and think that the atoms will vibrate more often, which is one of the most frequent misconseptions I have read about on scientific websites and forums about atomic motion. Every molecule, molecular solid or atomic solid has characteristic vibration frequencies in the range of 10^13 Hz due to their mass and force interactions. For example: If the frequency of a radiation source matches a molecules or atoms natural resonant frequency it begins to vibrate stronger, not more frequently! Now the energy of those vibrations can be transferred in solids due to whole lattice vibrations called phonons. I'm not trying to give a lecture here. But its such a common misconception that people say if you heat stuff, the frequency of the atomic vibrations increase, which is absolutely NOT true. It's the amplitude of the vibrations that gets larger. Of course this explanation was viewed at with classical mechanics, quantummechanically everything has to do with probability waves and distributions... but the probability of finding a particle will shift towards a higher distance if we give the system more energy. If you look at the asymmetric potential curve you get the idea... The frequency of atomic oscillations simply do not change, otherwise IR-Spectroscopy would not work, as peaks would shift around all the time being a strongly temperature dependant measurement method, which it is not! One thing you can get is overtones of vibrations at higher temperatures... The frequencies which change will eventually be those of the whole macroscopic lattice due to thermal expansion and changes in the elastic modulus of the solid.
I think why most people think that atoms change their vibration frequencies is due to incandescence... simply speaking if the amplitude of a vibrating system increases but the vibration frequency stays the same, the particles have to travel a longer distance in the same amount of oscillations. Thus ultimately your statement is correct that the particles have to move faster. Faster moving particles means that more energy is involved... Electromagnetic radiation is generated by the movement of charged particles in space, so at temperatures of around 800 Kelvin our eyes begin to see dim red light emitted from that object depending on its emissivity. At these temperatures the atomic vibrations are so intense that the strong acceleration and deceleration leads to the incandescent effect emitting red light. Plancks law, Wien's displacement law and the stefan boltzmann law are responsible for the shape of the function, the maximal emitted wavelength at a certain temperature and the intensity of the radiation... OK sorry this has escalated to become a lecture ;)