Never ending heat
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Discussion

JoolzB

Original Poster:

3,549 posts

279 months

Saturday 3rd December 2005
quotequote all
So we've had never ending light in an inside out bauble but what's the answer to this one.

There's a heater in a cold room that's perfectly insulated i.e. no heat loss. The heaters' element is set to 20 degrees C and the thermostat has thrown a wabbly and don't work no more. What happens to the temperature in the room, does it get to 20, stay at 20 or keep on rising?

Mikey G

4,898 posts

270 months

Saturday 3rd December 2005
quotequote all
you cant set an 'element' but you can set a thermostat


Not an answer though, at a guess i would say the temp stayed constant at whatever temp the thermostat failed

dave_s13

14,031 posts

299 months

Saturday 3rd December 2005
quotequote all
Temp will rise to the exact max output of the heater. Assuming there is zero heat loss.

AFAIK heat is not cumulative.

JoolzB

Original Poster:

3,549 posts

279 months

Saturday 3rd December 2005
quotequote all
Mikey G said:
you cant set an 'element' but you can set a thermostat


Not an answer though, at a guess i would say the temp stayed constant at whatever temp the thermostat failed

Yeah know what yer saying, that's why I tried to word it ina way that the element was at a constant 20

Muncher

12,235 posts

279 months

Saturday 3rd December 2005
quotequote all
If there is NO heatloss from the enclosed space, the space would continue to heat up until it got so hot, the heater failed. It would then stay at that temperature. If the energy can't be conducted, convected or radiated away it will increase the temperature of the "room" indefinitely.

dave_s13

14,031 posts

299 months

Saturday 3rd December 2005
quotequote all
Thats me talking $hite then!

JoolzB

Original Poster:

3,549 posts

279 months

Saturday 3rd December 2005
quotequote all
Muncher said:
If there is NO heatloss from the enclosed space, the space would continue to heat up until it got so hot, the heater failed. It would then stay at that temperature. If the energy can't be conducted, convected or radiated away it will increase the temperature of the "room" indefinitely.

It's an imaginery heater that would never fail due to the superior german parts used in its construction. Not that that changes your answer I guess as you're saying it would increase in temp indefinitely.

Another question then, is there an absolute max temperature like there is a minimum possible temp ie. -273?

JoolzB

Original Poster:

3,549 posts

279 months

Saturday 3rd December 2005
quotequote all
dave_s13 said:
Thats me talking $hite then!

Nobody's saying that mate.






It's just implied

BTW I don't know what the answer is my self and you may be right.

xiphias

5,889 posts

257 months

Saturday 3rd December 2005
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It would heat up and up and you ran out of fuel.

fid

2,431 posts

270 months

Saturday 3rd December 2005
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If the element's at a constant 20 celcius, regardless of how well the room's insulated, it ain't gonna go above 20 celcius.

dieseljohn

2,114 posts

286 months

Saturday 3rd December 2005
quotequote all
fid said:
If the element's at a constant 20 celcius, regardless of how well the room's insulated, it ain't gonna go above 20 celcius.


Bingo. However, the temperature the element will run at depends (assuming constant resistance) on both the current flow and the ambient temperature. So, if it is in fact the current flow that is constant the room will continue to heat until the element burns out or time ends.

For the temperature of the element to remain at 20° then, current flow at T=20° would equal zero and the system would reach equilibrium.

As for maximum temperature I guess it is whatever you would get if all of the energy in the universe was concentrated as heat in the smallest quantum of matter in the universe (whatever that is, a quark?).



>> Edited by dieseljohn on Saturday 3rd December 20:33

Muncher

12,235 posts

279 months

Saturday 3rd December 2005
quotequote all
There is no agreed-upon value, among physicists, for a maximum possible temperature. Under our current best-guess of a complete theory of physics, the maximum possible temperature is the Planck temperature, or 1.41679 × 10^32 Kelvins. This translates to about a quarter of a hundred nonillion degrees Fahrenheit (2.5 x 10^32). However, it is common knowledge that our current theories of physics are incomplete, thus leaving open the possibility of still higher temperatures.


So 250,000,000,000,000,000,000,000,000,000,000 degrees fahrenheit!

dilbert

7,741 posts

261 months

Saturday 3rd December 2005
quotequote all
Everyone is talking about the temperature of the room, but what about the pressure?

As the temperature rises, so does the pressure. If the room is evacuated, then the atoms of any minute traces of gas that exist will eventaully become plasma, then presumably the protons, neutrons and electrons will themselves separate.

It's important to remember that thermal heat cannot exist in a vacuum. Infrared EM energy can pass through space, but it only exhibits it's self as "heat" when it interacts with matter.

Edited to add;

This question is, in fact, exactly the same as the previous one about light.

>> Edited by dilbert on Saturday 3rd December 21:08

>> Edited by dilbert on Saturday 3rd December 21:17

anhamgrimmar

1,025 posts

261 months

Saturday 3rd December 2005
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isnt this complicatedly a dyson sphere?

>> Edited by anhamgrimmar on Saturday 3rd December 21:15

JoolzB

Original Poster:

3,549 posts

279 months

Saturday 3rd December 2005
quotequote all
anhamgrimmar said:
isnt this basically a dyson sphere?

There's nothing basic about a Dyson sphere.

dilbert

7,741 posts

261 months

Saturday 3rd December 2005
quotequote all
anhamgrimmar said:
isnt this basically a dyson sphere?


Now I've looked it up....... Probably!

simpo two

92,929 posts

295 months

Saturday 3rd December 2005
quotequote all
JoolzB said:
Another question then, is there an absolute max temperature like there is a minimum possible temp ie. -273?

Heat is expressed as molecular/atomic movement. The hotter it is, the faster they go. Absolute zero is such because that's when they stop, and you can't get slower than stop.

I remember my chemistry master saying that if all the molecules in a pint of beer happened to move the same way at once, the beer would jump out of the glass...

As for absolute maximum, well, if molecules, atoms etc vibrate faster and faster as temperature increase - what happens when that movement exceeds the speed of light? Will the matter disappear into a parallel universe?

Muncher

12,235 posts

279 months

Saturday 3rd December 2005
quotequote all
simpo two said:
JoolzB said:
Another question then, is there an absolute max temperature like there is a minimum possible temp ie. -273?

Heat is expressed as molecular/atomic movement. The hotter it is, the faster they go. Absolute zero is such because that's when they stop, and you can't get slower than stop.

I remember my chemistry master saying that if all the molecules in a pint of beer happened to move the same way at once, the beer would jump out of the glass...

As for absolute maximum, well, if molecules, atoms etc vibrate faster and faster as temperature increase - what happens when that movement exceeds the speed of light? Will the matter disappear into a parallel universe?


Surely at the moment the speed of light is as fast as anything can possibly travel?

8

1,423 posts

293 months

Saturday 3rd December 2005
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I'm sure I once read about someone making a photon travel faster than the speed of light by firing it through a tube filled with a certain gas. It exited before it had entered.

mybrainhurts

90,809 posts

285 months

Saturday 3rd December 2005
quotequote all
Warm in 'ere, innit...?