Question on thermodynamics, experts needed.

[AJS]

Hey all! Had a weird thought occur to me today. Keep in mind these questions apply with all things remaining constant.

Let's start off with coffee. If you have a hot coffee or a cold coffee in the same neutral container and both are equal distance away from their resting room temp, will the hot one cool down, and the cold one warm up, at the same rate and hit their resting temp at the same time? Or does the substance lose heat faster than it gains?

A little easier material to apply this question to is metal. Metal is known to be a good heat transfer and a resting temp can be quite cool. Same questions Applies. If a metal object is equal distance hot / cold of its room temp, will he hot steel hit room temp first or will the cold steel? Is it the exact same? I understand the heating / cooling of metal is different than something like wood, but within it's own category of metal, will hot metal / cold metal hit room temp the same? Will all items of their own category, wood, steel, iron, etc, have the hot / cold equal apart hit room temp at the same time within their own category? Or is the gain of heat of a given item different than the loss of heat.

____

I guess to sum it up. When it comes to the transfer of heat and all things being equal, does a given item lose heat faster than it gains (in relation to the same distance apart from room temp), or do some items gain heat faster than lose it or vice versa, or is heat transfer constant whether it's cold to hot, or hot to cold.


Thanks to all who help. Please provide a why if possible!

 

[AJS]

I guess the very easiest example to sum this up would be ...

If you have a metal at 100 degrees or one at 0 degrees and the resting temp is 50 which will hit the resting temp first.

Does that change based off matieral? Wood, ceramic, glass, etc.

(Not sure if temperatures actually work that way but theoretically ...)

 

[DDave]

Hey all! Had a weird thought occur to me today. Keep in mind these questions apply with all things remaining constant.

Let's start off with coffee. If you have a hot coffee or a cold coffee in the same neutral container and both are equal distance away from their resting room temp, will the hot one cool down, and the cold one warm up, at the same rate and hit their resting temp at the same time? Or does the substance lose heat faster than it gains?

A little easier material to apply this question to is metal. Metal is known to be a good heat transfer and a resting temp can be quite cool. Same questions Applies. If a metal object is equal distance hot / cold of its room temp, will he hot steel hit room temp first or will the cold steel? Is it the exact same? I understand the heating / cooling of metal is different than something like wood, but within it's own category of metal, will hot metal / cold metal hit room temp the same? Will all items of their own category, wood, steel, iron, etc, have the hot / cold equal apart hit room temp at the same time within their own category? Or is the gain of heat of a given item different than the loss of heat.

____

I guess to sum it up. When it comes to the transfer of heat and all things being equal, does a given item lose heat faster than it gains (in relation to the same distance apart from room temp), or do some items gain heat faster than lose it or vice versa, or is heat transfer constant whether it's cold to hot, or hot to cold.


Thanks to all who help. Please provide a why if possible!

I guess the very easiest example to sum this up would be ...

If you have a metal at 100 degrees or one at 0 degrees and the resting temp is 50 which will hit the resting temp first.

Does that change based off matieral? Wood, ceramic, glass, etc.

(Not sure if temperatures actually work that way but theoretically ...)

Greetings @AJS

Disclaimer: Sometimes my responses will spawn more questions than those they answer...

The rate constant for increase (or decrease) of temperature is the equal (assuming other details of the material don't change much), so the timing is the same regardless of the differences in temperatures or goal temperatures, but this does not mean you have to wait the same amount of time. As is the nature of time.

or

The temperature of the item converges exponentially to the temperature of the area surrounding it. This means you have to wait longer, if the difference is very small.

 

[Tranquility]

If you balance all the factors except for the temperature, they should transfer the heat at the same rate rather it is into the material or out to the world. Assuming your target is room temp and the temps you are checking on are above and below it to the same level, transfer is the same.

There would be a difference if you were at temperatures where you are getting some change of matter state (ice-liquid-steam-plasma), especially if you are transferring from liquid to steam and lose some of the material with the evaporation. There are other variables as well. But, the key to remember is everything is relative.

The check on this gets to the basic laws. If we have a closed system, which is what I assume you are talking about, energy cannot be created or destroyed. Depending on how you look at it, in both cases you are not only making a cool thing hotter, but also making a warm thing cooler. The heat is going to go somewhere, so do a thought experiment to provide the answer. If you look at the coffee, how long will it take to cool to room temp? Now, look at the air and surrounding items that will be affected by the heat transfer. How long will it take to warm up?

The same amount of time.

It just depends on which side, the warming or the cooling, you're looking at.