# Everything in a given environment have the same temperature

#### quasi426

Does everything in a given environment have the same temperature. For example does everything inside a refridgerator have the same temperature like a cup of water and a block of steel and a plastic cup. (say the setting of the fridge is at 5 C degrees, if a thermometer is placed on all these items, will they all yield a 5 C degree temperature reading.) Of course assuming these items have been in the environment for a long time and the environment is using energy to maintain this constant temperature.

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#### Meir Achuz

Homework Helper
Gold Member
The temperature does not depend on the type of material.
But, how cold something at a low temperature feels if you touch it depends on more than temperature. The coldness sensation also depends on the heat conductivity and the specific heat capacity of the material.. So steel at 5 C will feel colder than plastic at 5 C, because the heat flow into your hand is faster.

#### NewScientist

I have an answer already formed in my head but I don't want to give it away.

Why don't you consider the system by which the fridge regulates its temperature - the thermostat etc, and if the doors are completely air tight, and if the fridge won't radiate or absorb heat etc.

NS

#### Antiphon

The answer is yes, they all have the same temperature if you wait
for everything to reach equilibrium- for an ideal fridge.

This will never happen in a real refridgerator for all the things you cited.

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#### quasi426

Meir Achuz said:
The temperature does not depend on the type of material.
But, how cold something at a low temperature feels if you touch it depends on more than temperature. The coldness sensation also depends on the heat conductivity and the specific heat capacity of the material.. So steel at 5 C will feel colder than plastic at 5 C, because the heat flow into your hand is faster.
This is exactly what I was thinking. We feel heat conductivity and not temperature. Thanks. Does anyone have a biological reference?

#### reasonmclucus

An additional factor in human feeling of heat/cold is that whether something feels hot or cold depends in part on what a finger, for exampe, has touched previously. The standard experiment is to place a finger of one hand into a cup of hot water and the a finger of the other hand into a cup of cold water. Then place both fingers into a cup of luke warm water. The finger that was in hot water will feel cold while the finger that was in cold water will feel hot.

#### russ_watters

Mentor
quasi426 said:
This is exactly what I was thinking. We feel heat conductivity and not temperature. Thanks. Does anyone have a biological reference?
I'm not sure if this is what you mean, but if you touch a piece of metal and a piece of wood, both at room temperature, the metal will feel cold and the wood will not. This is because our sense of touch/temperature depends more on heat transfer rate than it does on temperature itself.

#### Danger

Gold Member
reasonmclucus said:
An additional factor in human feeling of heat/cold is that whether something feels hot or cold depends in part on what a finger, for exampe, has touched previously.
Quite correct. The brain adjusts its sensory inputs over a period of time. An old bar trick, for example, is to secretly pinch an ice cube between your thumb and forefinger for a while, and then bet someone that you can hold a lit cigarette by the ember without flinching. As long as you restrict it to a few seconds, you won't feel the heat and it won't cause a burn.
Another thing that seems counter-intuitive at first is that frostbite and a burn are essentially the same injury and feel the same. Somebody like Moonbear would be best to follow up on this.

#### ddesai

Meir Achuz said:
The temperature does not depend on the type of material.
But, how cold something at a low temperature feels if you touch it depends on more than temperature. The coldness sensation also depends on the heat conductivity and the specific heat capacity of the material.. So steel at 5 C will feel colder than plastic at 5 C, because the heat flow into your hand is faster.

Hmmm ... I am thinking it's the other way around. Metal, due to free electrons, conducts heat better than plastic. So heat will flow from your hand into the steal at a greater rate than it will from your hand to to the plastic.

#### quasi426

russ_watters said:
I'm not sure if this is what you mean, but if you touch a piece of metal and a piece of wood, both at room temperature, the metal will feel cold and the wood will not. This is because our sense of touch/temperature depends more on heat transfer rate than it does on temperature itself.

Yeah that is what I was saying. But I guess I said heat conductivity instead of heat transfer because they are similar.

#### Meir Achuz

Homework Helper
Gold Member
ddesai said:
Hmmm ... I am thinking it's the other way around. Metal, due to free electrons, conducts heat better than plastic. So heat will flow from your hand into the steal at a greater rate than it will from your hand to to the plastic.
Thank you. I did mean heat flow out of your hand.
Heat flow into your hand would be why hot metal in burns your hand, while wood doesn't.

#### Antiphon

Final comment-

If your hand is 92 degrees then a 92 degree peice of wood and steel will feel
the same. I've tried it.

#### quasi426

I've noticed that sometimes when one has a fever, they may not be able to tell how bad of a temperature increase they have incurred when one feels their own forehead as opposed to someone else feeling it.

"Everything in a given environment have the same temperature"

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