Which Cup Cools Down Quicker ?

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Offline neilep

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Which Cup Cools Down Quicker ?
« on: 08/07/2008 20:21:23 »
Dear Cupologists and Bra Wearers !

Cups are my all time favourite thing for filling with liquid and then drinking from !
Glasses are nice too...but I prefer a cup..or a mug actually.....but not a horse trough !....those are reserved for my annual bath ! [attachment=3619]





See these two photos of two cups ?

[attachment=3620]

and then this one ?

[attachment=3622]

Nice eh ?



Notice the shape of the cups ?....say the water within was very hot...boiling in fact !

Would there be a difference at the speed at which both cups of water cooled down ?

I wish I knew !!...Oh woe is me...how I wish I knew !! [:-[]

End my woe
Let me know !!
About H20 !



*le thanks*




Neil
Cup Handler

mwah mwah mwah mwah

xxxxxxxxxxxxxxxxxxxxxx




Men are the same as women, just inside out !

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Offline RD

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Which Cup Cools Down Quicker ?
« Reply #1 on: 08/07/2008 21:01:21 »
The cup with the greater  volume of water will take longer to cool, as its surface-area to volume ratio is lower,
 (“area” includes the area in contact with the cup).

If you have a thermometer you could perform this experiment and find out which cools faster,
 e.g. time how long each takes to cool from 90C to 60C.

Yes I did notice that the cup diameter increases slightly towards the top,
So the water in the fuller cup will have slightly larger area exposed to the air ,
But this is negligible compared with the additional thermal inertia of the larger volume of water.

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blakestyger

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Which Cup Cools Down Quicker ?
« Reply #2 on: 09/07/2008 12:37:18 »
In Newton's Law of Cooling the heat change (ΔQ) is proportional to the mass (m) so it looks as if the larger will cool slower.


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Offline neilep

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Which Cup Cools Down Quicker ?
« Reply #3 on: 09/07/2008 14:21:30 »
The cup with the greater  volume of water will take longer to cool, as its surface-area to volume ratio is lower,
 (“area” includes the area in contact with the cup).

If you have a thermometer you could perform this experiment and find out which cools faster,
 e.g. time how long each takes to cool from 90C to 60C.

Yes I did notice that the cup diameter increases slightly towards the top,
So the water in the fuller cup will have slightly larger area exposed to the air ,
But this is negligible compared with the additional thermal inertia of the larger volume of water.

Thank You RD

Yes, I was thinking that the fuller cup might actually cool down quicker because of the very reason you mention. But, your explanation helps me understand why not...ta.
Men are the same as women, just inside out !

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Offline neilep

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Which Cup Cools Down Quicker ?
« Reply #4 on: 09/07/2008 14:22:28 »
In Newton's Law of Cooling the heat change (ΔQ) is proportional to the mass (m) so it looks as if the larger will cool slower.



Thank You blakestyger

I appreciate your confirmation.

Cheers

Men are the same as women, just inside out !