Cooling beer problem
July 3rd, 2017 at 8:47:59 PM
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A refrigerator is kept at a constant temperature of 5 degrees.
A can of beer is placed in it with initial temperature of 25 degrees.
In one hour it cools to 15 degrees.
Assume that that the penguin that lives in the refrigerator not only turns the light on and off when you open the door but shakes the beer so that it maintains a constant temperature (and explodes in your face when you open it).
Hint: The rate of heat transfer is proportional to the difference between the temperature of object to the ambient temperature.
How long will it take to cool the beer to 10 degrees from the time it is placed inside the refrigerator?
A can of beer is placed in it with initial temperature of 25 degrees.
In one hour it cools to 15 degrees.
Assume that that the penguin that lives in the refrigerator not only turns the light on and off when you open the door but shakes the beer so that it maintains a constant temperature (and explodes in your face when you open it).
Hint: The rate of heat transfer is proportional to the difference between the temperature of object to the ambient temperature.
How long will it take to cool the beer to 10 degrees from the time it is placed inside the refrigerator?
"For with much wisdom comes much sorrow." -- Ecclesiastes 1:18 (NIV)
July 3rd, 2017 at 9:16:05 PM
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2 hours
July 3rd, 2017 at 9:24:58 PM
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^^ I'm not sure what the answer is... but pretty sure that's the one answer it isn't.
July 3rd, 2017 at 9:39:27 PM
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At those temperatures, the beer will freeze before you know it.
http://www.homebrewtalk.com/showthread.php?t=176193
http://www.homebrewtalk.com/showthread.php?t=176193
DUHHIIIIIIIII HEARD THAT!
July 3rd, 2017 at 10:32:16 PM
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My guess is around 1:15
July 3rd, 2017 at 10:49:23 PM
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I agree with ChesterDog.
I heart Crystal Math.
July 3rd, 2017 at 11:01:39 PM
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Unless the question is in Celsius, most beers are already frozen at 25°.
DUHHIIIIIIIII HEARD THAT!
July 4th, 2017 at 12:53:24 AM
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Quote: IbeatyouracesUnless the question is in Celsius, most beers are already frozen at 25°.
I think we have to assume Celsius, as 5°C=41°F which is a normal refrigerator temperature. The warm beer is 25°C=77°F.
It's a simple differential equation dH/dt= ω H , when t=0, H=25-5=20, when t=1, H= 15-5=10. H is exponentially related to t.
H=H0 * exp( ω t) so H0=20 is the original heat differential,
10=20 * exp( ω ) given the second condition so ω = - ln(2)
So solve for time t= τ when H = 5
5=20 * exp( - ln(2) * τ )
1/4 = exp( - ln(2) * τ ) so τ =2 hours
July 4th, 2017 at 5:34:26 AM
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First, ChesterDog is the winner with the first correct answer. I owe you a cold beer.
Second, the temperatures are given in Celsius.
Third, I apologize for that one being too easy. How long will it take to cool the beer to 5.1 degrees?
Second, the temperatures are given in Celsius.
Third, I apologize for that one being too easy. How long will it take to cool the beer to 5.1 degrees?
"For with much wisdom comes much sorrow." -- Ecclesiastes 1:18 (NIV)
July 4th, 2017 at 7:18:18 AM
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Quote: WizardFirst, ChesterDog is the winner with the first correct answer. I owe you a cold beer.
Second, the temperatures are given in Celsius.
Third, I apologize for that one being too easy. How long will it take to cool the beer to 5.1 degrees?
I get t = log [ ( 25 - 5 ) / ( 5.1 - 5 ) ] / log(2) = log(200) / log(2) = 7 hours 39 minutes.
July 4th, 2017 at 8:37:02 AM
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Quote: ChesterDogI get t = log [ ( 25 - 5 ) / ( 5.1 - 5 ) ] / log(2) = log(200) / log(2) = 7 hours 39 minutes.
Correct! You get a liter of beer for the extra credit.
"For with much wisdom comes much sorrow." -- Ecclesiastes 1:18 (NIV)
July 4th, 2017 at 9:07:50 AM
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Quote: WizardQuote: ChesterDogI get t = log [ ( 25 - 5 ) / ( 5.1 - 5 ) ] / log(2) = log(200) / log(2) = 7 hours 39 minutes.
Correct! You get a liter of beer for the extra credit.
Dammit. I didn't know there was a prize going begging, and I knew the answer :o)
Psalm 25:16
Turn to me and be gracious to me, for I am lonely and afflicted.
Proverbs 18:2
A fool finds no satisfaction in trying to understand, for he would rather express his own opinion.
July 4th, 2017 at 9:11:30 AM
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Beer is disgusting. Being rewarded with it would be punishment.
DUHHIIIIIIIII HEARD THAT!
July 4th, 2017 at 10:30:46 AM
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Math? Thermodynamics?
How many of you if confronte with this problem would simply open the refrigerator and drink the can of beer rather than whipping out a slide rule?
How many of you if confronte with this problem would simply open the refrigerator and drink the can of beer rather than whipping out a slide rule?
July 4th, 2017 at 10:56:16 AM
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Quote: FleaStiffMath? Thermodynamics?
How many of you if confronte with this problem would simply open the refrigerator and drink the can of beer rather than whipping out a slide rule?
I'll choose the slide rule.
"For with much wisdom comes much sorrow." -- Ecclesiastes 1:18 (NIV)
July 4th, 2017 at 11:17:22 AM
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Huh, interesting. I had to solve that problem when I was 14 as part of a competition called "physics olympics". It wasn't a beer though. I passed that round.
I failed the next round when I had to calculate the tides on Earth relative to the position of the moon. (Assuming the Earth was homogenously covered in water with no landmass. [Insert physicist assuming something absurd joke here.]) To this day I don't know how to do this.
I failed the next round when I had to calculate the tides on Earth relative to the position of the moon. (Assuming the Earth was homogenously covered in water with no landmass. [Insert physicist assuming something absurd joke here.]) To this day I don't know how to do this.
July 4th, 2017 at 1:44:54 PM
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Quote: CanyoneroHuh, interesting. I had to solve that problem when I was 14 as part of a competition called "physics olympics". It wasn't a beer though. I passed that round.
That is quite a problem for 14. Glad to have another genius on the forum!
"For with much wisdom comes much sorrow." -- Ecclesiastes 1:18 (NIV)
July 4th, 2017 at 11:18:45 PM
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are we talking real beer or American beer??
get second you pig
July 5th, 2017 at 6:11:37 AM
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Quote: ontariodealerare we talking real beer or American beer??
Winners choice between Lucky Lager, Burgie, and Miller.
"For with much wisdom comes much sorrow." -- Ecclesiastes 1:18 (NIV)
July 5th, 2017 at 6:53:17 AM
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Quote: WizardWinners choice between Lucky Lager, Burgie, and Miller.
Be the AP that you are and get them Olde English. 😎
DUHHIIIIIIIII HEARD THAT!
July 5th, 2017 at 8:59:44 AM
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Quote: IbeatyouracesBe the AP that you are and get them Olde English. 😎
I prefer Old Milwaukee. In part because they aren't so pretentious as to put an e after the "Old."
"For with much wisdom comes much sorrow." -- Ecclesiastes 1:18 (NIV)
July 6th, 2017 at 5:27:05 AM
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Quote: WizardI prefer Old Milwaukee. In part because they aren't so pretentious as to put an e after the "Old."
It's not meant to be pretentious; it's shtick about old vs. modern English. "ye olde brewery"
( and apparently "ye olde" is incorrect also https://en.wikipedia.org/wiki/Ye_olde )
July 6th, 2017 at 9:32:18 AM
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Quote: WizardI prefer Old Milwaukee. In part because they aren't so pretentious as to put an e after the "Old."
Yikes. There is lots of good beer out there!
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You want the truth! You can't handle the truth!
July 6th, 2017 at 9:35:30 AM
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Apparently, you guys didn't get my joke. OE is about the cheapest, if not THE cheapest beer there is.
DUHHIIIIIIIII HEARD THAT!
July 6th, 2017 at 10:08:33 AM
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Beer: Probably off topic but I'm a fan of Real Ale rather than gaseous stuff that some pubs sell. There's an organization called CAMRA which promotes it. Thus, if you look, there's some very good pubs around - these are two near me...
https://whatpub.com/pubs/HAS/00842/bookshop-alehouse-southampton
https://whatpub.com/pubs/HAS/00470/guide-dog-southampton
https://whatpub.com/pubs/HAS/00842/bookshop-alehouse-southampton
https://whatpub.com/pubs/HAS/00470/guide-dog-southampton
July 6th, 2017 at 9:53:40 PM
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It's a fake spelling that was started as a mock antiquity. The "Ye Olde _____" construction was being made fun of by 1896. So your disdain is well placed.Quote: WizardIn part because they aren't so pretentious as to put an e after the "Old."
