Keep the Heat B/Thermodynamics C

[harryk]

Always remember, all the other teams are subject to the same exact 'problems', if it does severely hinder your guessing accuracy, so it will to everyone else

[Frogger4907]

Always remember, all the other teams are subject to the same exact 'problems', if it does severely hinder your guessing accuracy, so it will to everyone else

That would then make winning the event luck. because know one can factor ALL of the variables.

[JSGandora]

Sorry to diverge from the conversation however I have a question. Is polystyrene considered commercial insulation? It is organic and granular.

[tornado guy]

That would then make winning the event luck. because know one can factor ALL of the variables.

Can't tell if you purposely did that or not..

[Frogger4907]

That would then make winning the event luck. because know one can factor ALL of the variables.

Can't tell if you purposely did that or not..

no I'm really tired sorry.

[ichaelm]

All of the problems that Frogger mentioned are legitimate problems, and the results of his experiment are reasonable by my testing. But all of those problems can be accounted for by the students' preparation. It reminds me of last year in optics, how the rules did not prevent supervisors from using mirrors with big annoying rims, which would throw off most teams' procedures. But the best teams were the ones who prepared for that, and did the best they could. You have found a variable that is hard to account for, Frogger. Now try and account for it!

Sorry to diverge from the conversation however I have a question. Is polystyrene considered commercial insulation? It is organic and granular.

I agree that plastics are generally organic. But since when is polystyrene granular? A foam is not granular. And even if you chose to chop it up into "grains" with a food processor, that doesn't make something granular. The word granular means that a substance has a certain smallest possible elementary form, which is big enough to be "visible". The smallest possible form of polystyrene would be some kind of hydrocarbon monomer, which is submicroscopic. Popcorn and sunflower seeds are granular because there is a noticeable smallest element: the kernel, or the seed.

So we can't use polystyrene, no matter if it's commercial or not. But still, you're really asking for a definition of "commercial insulation." It's subject to interpretation, but I interpret it like this: If it comes in a package that says "insulation" on it, then it's commercial insulation.

[Frogger4907]

All of the problems that Frogger mentioned are legitimate problems, and the results of his experiment are reasonable by my testing. But all of those problems can be accounted for by the students' preparation. It reminds me of last year in optics, how the rules did not prevent supervisors from using mirrors with big annoying rims, which would throw off most teams' procedures. But the best teams were the ones who prepared for that, and did the best they could. You have found a variable that is hard to account for, Frogger. Now try and account for it!

If it was one variable I would try to account for it. But it is many more than that. If they measured initial temp than it would be a workable situation.

[chalker]

Sorry to diverge from the conversation however I have a question. Is polystyrene considered commercial insulation? It is organic and granular.

Look at rule 3.b closely. It explicitly prohibits plastics. Polystyrene is a plastic (http://en.wikipedia.org/wiki/Polystyrene).

[chalker]

If it was one variable I would try to account for it. But it is many more than that. If they measured initial temp than it would be a workable situation.

How do you know it isn't a workable situation? Have you run multiple repeat tests? For all you know the various other variables you are concerned about tend to cancel each other out, allowing you to rather accurately predict the final temperature based upon initial conditions.

Regardless, this is a slippery slope you are going down. Let's say we do measure the initial temp once the beakers are in the devices. I can imagine someone then saying we need to take into account variables such as whether the device is close to a window (with the sun shining in), or directly under a HVAC vent (increasing the local air flow), or sitting on a wooden table versus a lab bench, or for exactly how long the supervisor left the temperature probe in the beaker, or what the temperature of the probe was before it was inserted, etc. etc. etc.

The bottom line is there is always a struggle between theory and practice. We have to create an event that is practical to run, which means there are tradeoffs to be made regarding the theory that is being tested.

[DeathTriangleCoach]

I want to chime in here in defense of the students that have posted. Each concern regarding the initial temperature of the water posted is valid and many of the replies include the word "suspect". This event has never been run anywhere, and is just now being tested in schools throughout the United States. As Regional Director, I have already heard from two other schools with the same concern about the initial temperature. The initial temperature needs to be taken as the device is closed. My students have thoroughly tested this 'transfer' problem and the average time of transfer is 30 seconds (can't safely be done faster than that...we do not want high schoolers pouring nearly-boiling water twice in less time than that) and the average temperature difference is about 12˚C, but is larger with higher initial bath temperatures. As science teachers/scientists, we work to eliminate variables and should only be testing one at a time. The goal of the event appears to be two-fold: 1. Build a device out of natural materials, including "granular organics" (this needs defining, by the way) to retain as much heat as possible, and 2. Be able to accurately predict the final temperature, which is IMPOSSIBLE without accurately knowing the initial temperature. There are at least 8 variables that have some effect on the initial temperature, all of which would be eliminated by taking the initial temperature once the water is in the device. As for difficulty for event supervisors to measure these initial temperatures individually, with staggered start (Rule 4.a.iv), there will be no problem for event supervisors, even if they have only one thermometer (most of which will have more than one).

You stated at least 3 times in your replies that you "suspect" an outcome. The difference between plastic and glass appears to be minimal, but the other two, it is significant. The problem with "suspecting" something is that it has not been tested. It has now been tested and there is a problem. The rules have been written to allow "luck" and "guessing" to be a factor...not good science. Please change the rule to state the initial temperature will be taken once the water is IN the device. [By the way, the state of Kansas just announced this morning that is has already decided that the initial temperature will be taken as the lid closes.]