Concept of "Cold"
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Concept of "Cold"
I recently read that there is no such thing as "cold" according to thermodynamics. The sensation of "cold" is actually really just an absence of heat. How then, does does adding ice to hot coffee cause it to become more cold if we are just adding quantities of substance that are close to/absent of heat?
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Re: Concept of "Cold"
Adding ice to hot coffee lowers the temperature of the overall substance because the heat from the coffee transfers to the ice therefore "filling" in the absence of heat of the ice resulting in a decrease in temperature of the coffee.
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Re: Concept of "Cold"
This is simply the second law of thermodynamics: how heat flows naturally from an object at higher temperature to an object at lower temperature. You need work to force the heat in the other direction (this is what Air Conditioner and Refrigerators do). I agree with the example stated above: it really simplifies the concept.
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Re: Concept of "Cold"
First of all, consider the ice the 'system' and the coffee the 'surroundings'. The melting of the ice is an endothermic reaction, it requires heat to occur, so the q of the system increases. According to the first law of thermodynamics, the q of the system = —q of the surroundings, so if the q of the system is increasing, the q of the surroundings is decreasing. Therefore the surroundings (the coffee) is cooled.
Conceptually heat and a cold are a lot like light and dark. There is technically no such thing as 'darkness' only the absence of light. Cold is merely our word for the absence of heat.
Conceptually heat and a cold are a lot like light and dark. There is technically no such thing as 'darkness' only the absence of light. Cold is merely our word for the absence of heat.
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Re: Concept of "Cold"
You feel cold when heat is flowing out of you and feel warm/hot when heat is flowing into you (say your hand when you hold a hot cup of tea). The temperature decreases when you add ice because heat is being transferred into the ice away from the liquid, lowering the temperature of the liquid.
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Re: Concept of "Cold"
Heat flows naturally from an object at a higher temperature to an object at a lower temperature. Adding ice will continue to lower the temperature of the liquid that's not surrounding the ice. Ice will lower the overall temperature of the coffee.
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Re: Concept of "Cold"
Adding ice causes the coffee to become colder because the ice is taking heat away from it. The heat is being transferred from the coffee to the ice cube. I guess you can think of it as the ice not making the coffee cold, instead it's really just taking away the hot.
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Re: Concept of "Cold"
Well, in that example there is an absence of heat. The coffee loses heat, therefore there is the absence of heat.
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