Physics Question

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C

carmana

Guest
Can an arangement of dissimular metals get hot whe they get cold
 
T

theridane

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Try rephrasing the question, provide an example or two, etc.
 
C

carmana

Guest
can an arangement of dissimular metal{I don't know what they could be] get hot when they get cold

ie a rod placed in freezing water gets hot, air, snow or ice?
 
S

Shpaget

Guest
Matter (metal or not) won't get warmer because you cool it down.
Some other source of energy must be present.

However, radioactive materials do heat up during radioactive decay but cooling them down would only slow down the decay rate resulting in less heat being generated.

There is a possibility that some material undergoes a chemical reaction when it comes into contact with some other substance, but not because it is cooled down.
 
C

carmana

Guest
IN other words, two three four, 10, dissimular metals/alloys are fussed, twisted, lamernated together so that when they get cold they argu and get hot
 
S

Shpaget

Guest
No.
If they were going to get hot they would get hot while still warm (room temperature). Cooling them down will not trigger the reaction.
 
C

carmana

Guest
What about harnissing expantion as a water pipe bursts when it freezes.
 
S

Shpaget

Guest
Tell me, is there a point in this?
It's always easier to heat something than to cool it down.
If you need a "cold detector" a simple bimetal will do just fine. When it cools down, it deforms and closes an electrical circuit and with electricity you can do pretty much anything.

So, what do you need this material for?
 
C

carmana

Guest
I live in Bulgaria where it can down to -20 for mouths it cost afortune to keep warm but that would nothing to the cost of freezing the back garded let alone the country

In the universe somewhere there must be something that gets hot when it gets cold
 
R

ramparts

Guest
carmana, that's an interesting question :) How can something get hot if it gets cold? Hot and cold are opposites. Sounds like looking for something that gets big when it gets small. Sounds like a logical impossibility to me.
 
O

origin

Guest
This OP triggered a thought (which for me is always dangerous), how about using the delta-T to generate electricity from a thermoelectric metal (like thermocouples). If one end of a rod is sunk into the ground 20 ft or so and the other end is above ground then the temperature difference would generate an electricial current - it would also generate a current in the summer, due to the delta-T.

This may be a silly idea because I have no idea what the voltage or current would be so it may take 2.5 bazillion rods to generate a meaningful current. :?: But I just thought I would throw it out there....
 
C

carmana

Guest
Origin, what about if one end of the thermercouple was outside the houe at -20 the otherend inside the house at +20c
 
O

origin

Guest
carmana":37fdiabh said:
Origin, what about if one end of the thermercouple was outside the houe at -20 the otherend inside the house at +20c
I think it is best to let the better informed members of this forum destroy this idea before we begin to design the system. ;)
 
S

Shpaget

Guest
You definitely do not want to put one end of it inside the house since it works on the principle of equalizing temperature so it would make your house colder than it already is.
Best placement of such thing would be - one end in the air with a lot of surface to "capture" the "cold" and the other end in a river that doesn't freeze during the winter, or like origin said deep under the surface of the earth (approximately 15 meters should probably be enough).

The problem is that this method does not produce much electricity and it has very low efficiency.

It would be MUCH cheaper to make better insulation on the houses. 8 centimeters of styrofoam on the outside walls is pretty good insulation. Double glass windows (preferably with vacuum between) will also help a lot and a good layer of wool under the roof (15-20 cm) will keep you warm even in the coldest weather.
The cost of these investments would probably pay itself back in just a few years just from lower price of heating.

Also the method of your current heating is very important. Regular fireplaces (wood) are very ineffective and can actually draw the warm air out of the house and pull the cold air in. Maybe you should look into gas or electric heating.
However I would still recommend good insulation.
 
U

undidly

Guest
Shpaget":gls7mpg2 said:
Matter (metal or not) won't get warmer because you cool it down.
Some other source of energy must be present.

However, radioactive materials do heat up during radioactive decay but cooling them down would only slow down the decay rate resulting in less heat being generated.

There is a possibility that some material undergoes a chemical reaction when it comes into contact with some other substance, but not because it is cooled down.
""radioactive materials do heat up during radioactive decay but cooling them down would only slow down the decay rate resulting in less heat being generated.""

The decay rate does not slow down.
 
S

Shpaget

Guest
undidly":283w44fn said:
The decay rate does not slow down.
Yeah, that is absolutely correct (at least for the temperatures in some reasonably attainable ranges).
 
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