predicting temperature loss over time..

[SystemParanoia]

Been confusing myself for a few mins on how to predict how fast items will loose temperature once placed the fridge.

Im curious for no real reason other than knowing that ill be able to calculate things for the next day or 2 until I cant be botherd to any more

if i placed a can of coke in the fridge* at room temp, how can I calculate how long until its chilled to fridge ambient? ( without timing it with a test can and just using that time as reference for the future lol )

* I am aware that depending on the size, type and power of the fridge figures can vary

[Jasandjules]

IIRC (it's been a long time for me) you need to worry about the specific heat capacity and it depends upon the temperature differential between the item and the environment.

[SystemParanoia]

well my fridge doesn't have a digital temp readout on the front, but I guess its about 3-4 deg c

and lets assume the can is a balmy 19 deg c

[Jasandjules]

Ok, then you want to look here

http://www.physicsclassroom.com/class/thermalP/u18...

I think, and it will give you the info you need to input the required figures (or guesswork!) to work out the rate of heat transfer.

[SystemParanoia]

i shall have a read of this. thank you

[R300will]

monumentally complicated unless you use a uniform substance like water. Spec heat is 4.18j/g/C? assume temperature in fridge is constant as well and the temp of water is known before you put it in and you could get close i think.

[BarnatosGhost]

dibbers006 said:

Have you ascertained that the interior light is actually turning off when you close the door, as this could be skewing your ambient readings.

You are a mischievous imp.

[Simpo Two]

Can the centre of the object ever reach EXACTLY the same temperature as the outside?

I once pondered how much the temperature would go up on Pluto (after requisite time) if I struck a match on Earth. After pondeirng the inverse of infinity, I decided that heat might be a quantum thing and so it would always be one notch away. Or an electron jump, or summink.

[R300will]

Simpo Two said:

Can the centre of the object ever reach EXACTLY the same temperature as the outside?

I once pondered how much the temperature would go up on Pluto (after requisite time) if I struck a match on Earth. After pondeirng the inverse of infinity, I decided that heat might be a quantum thing and so it would always be one notch away. Or an electron jump, or summink.

I don't think the heat would ever get to pluto.

[1point7bar]

If the match caused the earth's total temperature to be 1 nominal unit higher then when the sun becomes a red giant that nominal unit is added to the thermal value of the helium fusion? Difficult to know if the energy becomes planetary nebular or white dwarf but both would affect the temperature of pluto. So possibly
internet science bulls**t award winning material here.

[Eggman]

I seem to remember this type of calculation being one of the only practical applications of calculus we were taught at school.

I still remember the question we were set, which was to calculate the power of heater required in a light aircraft to maintain a certain cabin temperature and being impressed by how useful it seemed to be able to do that. I don't think I've needed calculus since, which is just as well because I've forgotten how to do it!

[Simpo Two]

Eggman said:

I still remember the question we were set, which was to calculate the power of heater required in a light aircraft to maintain a certain cabin temperature and being impressed by how useful it seemed to be able to do that.

I'd have fitted a thermostat!

[BarnatosGhost]

Simpo Two said:

Can the centre of the object ever reach EXACTLY the same temperature as the outside?

I once pondered how much the temperature would go up on Pluto (after requisite time) if I struck a match on Earth. After pondeirng the inverse of infinity, I decided that heat might be a quantum thing and so it would always be one notch away. Or an electron jump, or summink.

It could, since not only is the outside/environment affecting the object, but the object is affecting the outside/environment. Both tending towards each other.

The ultimate fate of the universe is Heat Death, when there are no temperature gradients at all, anywhere.

[1point7bar]

BarnatosGhost said:

The ultimate fate of the universe is Heat Death, when there are no temperature gradients at all, anywhere.

Astrophysically probably, but biologically we(they) might not go quietly into the night.

[Simpo Two]

BarnatosGhost said:

Simpo Two said:

Can the centre of the object ever reach EXACTLY the same temperature as the outside?

I once pondered how much the temperature would go up on Pluto (after requisite time) if I struck a match on Earth. After pondeirng the inverse of infinity, I decided that heat might be a quantum thing and so it would always be one notch away. Or an electron jump, or summink.

It could, since not only is the outside/environment affecting the object, but the object is affecting the outside/environment. Both tending towards each other.

The ultimate fate of the universe is Heat Death, when there are no temperature gradients at all, anywhere.

I have another match...

[Use Psychology]

i think that life is a spontaneous property of a system (the universe) that is out of equilibrium (we have big islands of matter and heat dotted throughout emptiness). living things are great at dissipating energy as heat.

[dickymint]

You'd think Coke would have put the info on the can.

[1point7bar]

Use Psychology said:

i think that life is a spontaneous property of a system (the universe) that is out of equilibrium

You are deterministic about randomness.

How?

[Use Psychology]

lots of systems self organise to return to equilibrium, for example oils you heat a thick oil from the bottom (e.g. in a saucepan) you will see hexagonal-shaped cells develop. This is an emergent property of the system (a pan full of oil that is hotter at the bottom than it is at the top, i.e. out of equilibrium) that acts to move the system back towards equilibrium (same temperature throughout).

[1point7bar]

'I think' is deterministic.
'spontaneous' is randomness.

properties of a system is deduction.