Thermodynamics B/C

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Re: Thermodynamics B/C

Post by bt03 »

chalker wrote:
bt03 wrote: So, is the event no longer a competition in insulation and rather on prediction?
I'd tried screwing with the numbers according to the score formula, but it seems in favor of the lower HRF and better PS. Quite strange.

TL;DR: How does a team with a high PS and low HRF score better than a team with a high PS and high HRF?
From a simplistic standpoint, yes the focus is more on prediction vs. performance. Keep in mind this is a physics committee event, so we have a general philosophy of ensuring events include both theory and practice. That's why the written test is worth so many points. Note it's perfectly acceptable in our minds for a team that aces the written test and completely bombs the device testing to rank higher than a team that does mediocre on both.

If you look at the rules from past seasons, you'll note that we used to prohibit a lot of types of materials from the devices. We made the deliberate change to allow virtually any material now, but have the scoring reward prediction more than performance. This ensure that the competition doesn't end up being a race to spend more and more money on exotic materials.
That's interesting to read. I am interested in what you mean by theory and practice; I am assuming ideal v. practical?
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Re: Thermodynamics B/C

Post by chalker »

bt03 wrote: That's interesting to read. I am interested in what you mean by theory and practice; I am assuming ideal v. practical?
Theory is the written test portion - how well do you know the various topics in the area?
Practice is the device testing portion - how well can you apply some of the topics to an actual device?

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Re: Thermodynamics B/C

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chalker wrote: Practice is the device testing portion - how well can you apply some of the topics to an actual device?
The topic of the emphasis with prediction over retention also leads to the next point about the IWB. At my block during the competition, nobody bothered with the ice water, which was simply a bag of ice slowly melting from the heat of the room, which I would assume would be poured into the competitor's beakers at their discretion.
Anyway, was the purpose of the ice water was to support the idea of the prediction, where a team with a relatively high HRF could reduce it in order to support their prediction score? Because in that case, theoretically, assuming everyone did well on the test, people could bring in a poorly constructed device and use the IWB to predict well and get a high PS, which doesn't support the idea of constructing a good insulator in order to retain heat and ensure that people ran tests on the device in order to predict well.
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Re: Thermodynamics B/C

Post by JoeyC »

bt03 wrote: Another team was also spot-on on their predictions (man, is the event dumb luck?), but heat retention was slightly higher (about 15 degrees, still good).
Test was relatively easy, so no comment there. (That is something I will never find myself saying given how astronomically impossible those practice tests were for a B divisioner).
That team with the spot-on prediction and 15 degree drop ended up placing better than the team with the lesser degree drop.
So, is the event no longer a competition in insulation and rather on prediction?).
In response, the event is composed of quite a bit dumb luck, as are all build events, this one just more so. The prediction score is more important then HREF because the PS is what matters in real world applications.
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Re: Thermodynamics B/C

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JoeyC wrote:In response, the event is composed of quite a bit dumb luck, as are all build events, this one just more so. The prediction score is more important then HREF because the PS is what matters in real world applications.
It's interesting to how much dumb luck there is, because my team actually came up with a general formula used from series of tests that came out to be accurate to about 1.5 degrees give or take. The reason why I was inquiring about the scoring of the competition is in general, a better insulated device will be sure to have more precise predictions, compared to a device that has some variation but a prediction came out to be pure luck.

However, in the spirit of solving the problem and not a rush for expensive materials as chalker said, I guess the prediction score tries to deter teams from flaunting. The only concern I have is teams won't put in the effort in attempting to construct something that can insulate and end up doing better than a team that put in the effort with test runs, yet their predictions are slightly off.
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Re: Thermodynamics B/C

Post by Justin72835 »

On a completely unrelated note, has anybody had success using a vacuum as a means of insulation? It seems like a farfetched idea but this is a question that I've had on my mind for a while now.
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Re: Thermodynamics B/C

Post by CookiePie1 »

Justin72835 wrote:On a completely unrelated note, has anybody had success using a vacuum as a means of insulation? It seems like a farfetched idea but this is a question that I've had on my mind for a while now.
We were thinking of trying to do that, but we couldn't find a thermos that was big enough, so we just stuck to using aerogel
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Re: Thermodynamics B/C

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Justin72835 wrote:On a completely unrelated note, has anybody had success using a vacuum as a means of insulation? It seems like a farfetched idea but this is a question that I've had on my mind for a while now.
I mean, anything is possible. We just used a simple styrofoam box which was consistent, and had some polyurethane insulation. Small and simple, easy to de-construct when needed (has it happened to anyone btw?). I’ve seen teams even use tin cookie cans!
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Re: Thermodynamics B/C

Post by benchwarmer »

Prediction Score is a nice idea. Yes, you should know how your device perform, if you spend enough time collecting/charting the temperature over time. But the temperature that you chart depends on how the water was dispense. During testing with your own tool and in your environment, you have the control to swiftly move the water or come up with the better to measure and capture the hot water in such a way that heat loss is minimized.
But at the actual event, you don't have that control . So much heat could be lost due to how the event was run.
For example:
* Distant between testing station and water boiling station can be far apart. Due to facility and safety...that's understandable. So the hot water must be dispensed into an open container and carry over to the testing station. HEAT LOSS.
* No proper/sophisticated device to measure the water accurately. Graduate cylinder is the only economical mean of measuring it. Which mean time spent pouring hot water into cylinder. Pause to take accurate reading. In the event that too much water was poured, ES must empty some of that water out of the cylinder. MORE HEAT LOSS.
* By the time water arrived at the station, it would drop by 10 °C(guessing). Then more time is need to pour water into beaker and seal it. may be another 5 °C is lost.
If your smart, then your estimate must account for how much temperature was dropped from the initial dispensing up to when it arrive and seal at the beaker. There may be some educated guess in the work, but there's a lot of LUCK for this portion of the event.
So it is possible have low HRF and best PS which will beat out device with HRF and low PS.

Perhaps it's best to consider PS score as tie breaker. Like how Tower does in their event.
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Re: Thermodynamics B/C

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benchwarmer wrote:Prediction Score is a nice idea. Yes, you should know how your device perform, if you spend enough time collecting/charting the temperature over time. But the temperature that you chart depends on how the water was dispense. During testing with your own tool and in your environment, you have the control to swiftly move the water or come up with the better to measure and capture the hot water in such a way that heat loss is minimized.
But at the actual event, you don't have that control .
I completely agree that heat loss is a significant factor in how one’s competition can go; however, if one were to test their device and have enough significant data points, they can still be able to make an educated guess on the final temperature. The issue that I had was a person with the same PS as another person but had a slightly higher HRF can still do worse than a person with the slightly lower HRF, but both people have the same PS and test score, for our purposes.

If you realized in the scoring of the PS, it is basically the accuracy formula divided by the final internal temperature, which by prior posts IMO is to ensure that the teams with a decent insulator compared to a great insulator can still rack up points for an accurate prediction and have a poor HRF, as dividing into a lower internal > higher internal. Now that I think about it, the HRF is virtually pointless as a team may try to get a low HRF in order to get more points for prediction as the cooling curve is steeper.

Now, I may seem picky on how the rules are interpreted, but it is just my opinion on how during the device testing portion, it may seem slightly unfair that a team that put effort in constructing a great insulator with a great prediction can get a lower score to a team with a decent insulator with a great prediction. I guess it’s time to focus on studying for the test portion!

I might be incorrect, but I believe the PS is already a tie breaker (either the 2nd or the 3rd TB)
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