Surface Area Cooling Laws for a Physics Science Fair Experiment

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The discussion focuses on the application of cooling laws related to surface area for a physics science fair experiment involving jars with varying surface areas filled with hot water. Participants suggest using Newton's law of cooling, which states that heat conduction is proportional to surface area and temperature difference. Clarification is provided that while Newton's law emphasizes temperature differences, it also considers surface area as a significant factor in heat transfer. The conversation highlights the importance of understanding both temperature and surface area in the context of heat loss. Overall, Newton's law of cooling is identified as the relevant principle for the experiment.
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Hi guys,

I'm doing a physics science fair, and I was just wondering if you guys know any cooling laws related speifically to surface area.

You see, for my science fair, I got three jars that had the same volume, but different surface areas. Then I filled them with hot water to see which one could come to room temperature fastest.

I need a law that I was supposedly "verifying" for my experiment.
I'd really appreciate any information.

Thanks!
 
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You're looking for Newton's law of cooling:

http://en.wikipedia.org/wiki/Newton's_law_of_cooling

Heat conduction (energy per unit time) is linearly proportional to the surface area.

- Warren
 
chroot said:
You're looking for Newton's law of cooling:

http://en.wikipedia.org/wiki/Newton's_law_of_cooling

Heat conduction (energy per unit time) is linearly proportional to the surface area.

- Warren

hmm.. I don't kno.. isn't Newton's law about the difference in temperatures between the two things? I need something that deals with surface area and heat loss.

Am I right, or am I just confused?
 
Look at the equation. A is the area. As I said, the heat conduction varies linearly with the area.

- Warren
 
_BaBy_PhAt_ said:
hmm.. I don't kno.. isn't Newton's law about the difference in temperatures between the two things? I need something that deals with surface area and heat loss.

Am I right, or am I just confused?
You are correct in that Newton's law deals with a difference in temperature. It gives the energy transfer between objects of different temperature, but there is more to it then just temperature.

The temperature of a match is about the same as that of a bonfire (both are burning wood) but the difference in the amount of heat transferred by the 2 sources is huge. Newton's law assumes that the key factor in the difference is the surface area of the 2 sources.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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