Thermodynamics B/C

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Re: Thermodynamics B/C

Post by UTF-8 U+6211 U+662F »

CookiePie1 wrote:
John Richardsim wrote:
Alex-RCHS wrote: Do you mean 60C before or after pouring the water in? I’ve found that the water drops about 10 degrees just after pouring it in.
For me, that's a 60 degree bath temperature before pouring.

(When I was getting data ready for the Solon invite, I only went by the temperature after pouring...my prediction ended up being 9 degrees too high...)
I always make a 60° water bath before pouring. The rules say that "event supervisors must announce the temperature of the source water bath", so the way the event should be run, it would be a constant temperature water bath that everyone's water comes out of. Since it is run this way, it does cause for a significant amount of heat loss, and since everyone's work areas are different distances from the water station, it makes quite a difference in heat retention. Now it's basically impossible to run this event perfectly, and there will be discrepancies no matter what.

So kudos to the event supervisors who run this event.
Fortunately, we're allowed to bring our own thermometers :)
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Re: Thermodynamics B/C

Post by Alex-RCHS »

What kind of temperature drops are you guys seeing after pouring the water in? For us, 100ml from a 90 degree bath ends up at about 77 degrees immediately after pouring.
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Re: Thermodynamics B/C

Post by CookiePie1 »

Alex-RCHS wrote:What kind of temperature drops are you guys seeing after pouring the water in? For us, 100ml from a 90 degree bath ends up at about 77 degrees immediately after pouring.
Our temperature drops down to 72 right after pouring, but that might be because my house has a rather low room temperature, about 18°C.
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Re: Thermodynamics B/C

Post by 5uper5tring »

Does the testing time start from the moment you receive water or from the moment the beaker is placed in the device?
Can you use your own thermometer to measure the initial water temperature (after it is poured into device) before making the prediction?
Thanks!
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Re: Thermodynamics B/C

Post by John Richardsim »

Alex-RCHS wrote:What kind of temperature drops are you guys seeing after pouring the water in? For us, 100ml from a 90 degree bath ends up at about 77 degrees immediately after pouring.
That's pretty similar to mine.
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Re: Thermodynamics B/C

Post by robloxparodies »

Alex-RCHS wrote:
John Richardsim wrote:
robloxparodies wrote: Thank you! On average, what's the ideal difference of temperature to make sure your device works? When I tested my device using 150 ml of 60 C water, the final temperature was 50 C Is this good?
That's about what I've been getting too.
Do you mean 60C before or after pouring the water in? I’ve found that the water drops about 10 degrees just after pouring it in.
it was 60 C before pouring, sorry for the late reply
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Re: Thermodynamics B/C

Post by arv101 »

5uper5tring wrote:Does the testing time start from the moment you receive water or from the moment the beaker is placed in the device?
Can you use your own thermometer to measure the initial water temperature (after it is poured into device) before making the prediction?
Thanks!
You are allowed to use your own thermometer. As for the timing I don't think the difference between receiving and putting in your hot water in your device should be that much (max 5 sec), so it doesn't really matter. From all the competitions I've been to no one measures time that accurately.
What did the thermometer say to the graduated cylinder?
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Re: Thermodynamics B/C

Post by TheChiScientist »

I find it annoying how they say the water temperature is say 70 C but when it ends up in our beaker it has dropped to 55 C. Anyone got a way to combat this problem or it pointless as it is most likely a event supervisor run problem? :?:
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Re: Thermodynamics B/C

Post by bt03 »

TheChiScientist wrote:I find it annoying how they say the water temperature is say 70 C but when it ends up in our beaker it has dropped to 55 C. Anyone got a way to combat this problem or it pointless as it is most likely a event supervisor run problem? :?:
As the others have pointed out, there is no way for the event to be run without any discrepancies, so it is not always going to be your fault. Always measure the temperature after the water is poured in, and make sure that your formulas that you use to predict the temperature is changed in accordance to Newton's cooling curve law. I'm sure you can do the math ;)
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Re: Thermodynamics B/C

Post by TheChiScientist »

bt03 wrote:
TheChiScientist wrote:I find it annoying how they say the water temperature is say 70 C but when it ends up in our beaker it has dropped to 55 C. Anyone got a way to combat this problem or it pointless as it is most likely a event supervisor run problem? :?:
As the others have pointed out, there is no way for the event to be run without any discrepancies, so it is not always going to be your fault. Always measure the temperature after the water is poured in, and make sure that your formulas that you use to predict the temperature is changed in accordance to Newton's cooling curve law. I'm sure you can do the math ;)
Okay thanks its nice to know I am not the only one struggling. ;)
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