Thermodynamics B/C

[Justin72835]

So basically, only the insulation immediately surrounding the beaker should matter. There shouldn’t be any empty space or else that will contribute to a greater surface area. Anything else beyond the layer of insulation touching the beaker will only serve to help with heat retention.

[TheChiScientist]

Yup. Basically, that is it.Thermo for dummies.

[JoeyC]

Does anyone know what the time lapse graphs really contribute/why scioly made them for points? On scioly.org, the graph is portrayed as someone testing a device at various temperatures and recording what the temperature was every 3 minutes. I always almost forget them because they have nothing to do with the goal of the device testing; to predict the ending temperature. In fact, the graphs are actually really easy to make, and you don't even necessarily need to test your device to make all the graphs (first test gathers data for cooling equation, no need to actually test the device for the rest, just plug in variables, if your constants such as your surrounding temperature are constant).
Concluding, why are the plot graphs worth points if they aren't actually contributing to the main points of the event, leading to the poising of the question:
Should the plot graphs be removed from the event, or modified so they better fit the event's purposes and intents.

[JoeyC]

Here is the plot example. Is it outdated? It's called Keep the Heat, which refers to the 2013 version of thermo, but the 2018 rule manual says that if we wish to see an example of the plot that we should go to scioly.org, and this is the only plot I have found.

https://www.soinc.org/sites/default/fil ... 111008.pdf

[John Richardsim]

Does anyone know what the time lapse graphs really contribute/why scioly made them for points? On scioly.org, the graph is portrayed as someone testing a device at various temperatures and recording what the temperature was every 3 minutes. I always almost forget them because they have nothing to do with the goal of the device testing; to predict the ending temperature. In fact, the graphs are actually really easy to make, and you don't even necessarily need to test your device to make all the graphs (first test gathers data for cooling equation, no need to actually test the device for the rest, just plug in variables, if your constants such as your surrounding temperature are constant).
Concluding, why are the plot graphs worth points if they aren't actually contributing to the main points of the event, leading to the poising of the question:
Should the plot graphs be removed from the event, or modified so they better fit the event's purposes and intents.

Actually, the graphs have a lot to do with the device testing. I'm not sure what your method is for predicting the final temperature, but mine is completely dependent on using the graphs. (I don't use Newton's law of cooling.)

The purpose of including them in scoring is that it is an incentive to students to not just show up with a device and guess. It's not meant to be difficult to make the graphs; it's meant to get students to visualize how different variables affect water temperature.

[JoeyC]

How do you make your predictions? I test my device to get data points and then for each water interval make a scatterppot with axi initial temperature and ending temperature and the notes use my trusty TI to get the quadratic function from the plot. I then use given function to predict. I use graphs, but (sorry if this is tunnel vision) how a plot that shows the decreasing temperature of the water inside their device helps in predictions; they only give values for 1 possibility each (ex: 75ml 87C), and unless you make one for each temperature and water interval, I don't see how it effectively aid so in predictions.

[UTF-8 U+6211 U+662F]

How do you make your predictions? I test my device to get data points and then for each water interval make a scatterppot with axi initial temperature and ending temperature and the notes use my trusty TI to get the quadratic function from the plot. I then use given function to predict. I use graphs, but (sorry if this is tunnel vision) how a plot that shows the decreasing temperature of the water inside their device helps in predictions; they only give values for 1 possibility each (ex: 75ml 87C), and unless you make one for each temperature and water interval, I don't see how it effectively aid so in predictions.

Given a cooling curve, one can (attempt to) make a formula that predicts the temperature based on time, starting temperature, and volume of water. Using this formula, one can then make a prediction. Of course, it would certainly be more effective to just use the ending temperatures, but that would require many more tests, each one taking thirty minutes and additional time to attempt to control the temperature of the water after pouring, the volume after boiling, etc.

[CookiePie1]

How do you make your predictions? I test my device to get data points and then for each water interval make a scatterppot with axi initial temperature and ending temperature and the notes use my trusty TI to get the quadratic function from the plot. I then use given function to predict. I use graphs, but (sorry if this is tunnel vision) how a plot that shows the decreasing temperature of the water inside their device helps in predictions; they only give values for 1 possibility each (ex: 75ml 87C), and unless you make one for each temperature and water interval, I don't see how it effectively aid so in predictions.

Given a cooling curve, one can (attempt to) make a formula that predicts the temperature based on time, starting temperature, and volume of water. Using this formula, one can then make a prediction. Of course, it would certainly be more effective to just use the ending temperatures, but that would require many more tests, each one taking thirty minutes and additional time to attempt to control the temperature of the water after pouring, the volume after boiling, etc.

I did 26 tests of our device, and we didn't even do all volumes/temperatures, and our prediction was only 1° off at states. I feel like making a formula is theoretically a good idea, but in practice there are several things that could affect it (room temp, humidity, etc) so it really is better to just actually do the tests.

[Justin72835]

How do you make your predictions? I test my device to get data points and then for each water interval make a scatterppot with axi initial temperature and ending temperature and the notes use my trusty TI to get the quadratic function from the plot. I then use given function to predict. I use graphs, but (sorry if this is tunnel vision) how a plot that shows the decreasing temperature of the water inside their device helps in predictions; they only give values for 1 possibility each (ex: 75ml 87C), and unless you make one for each temperature and water interval, I don't see how it effectively aid so in predictions.

Given a cooling curve, one can (attempt to) make a formula that predicts the temperature based on time, starting temperature, and volume of water. Using this formula, one can then make a prediction. Of course, it would certainly be more effective to just use the ending temperatures, but that would require many more tests, each one taking thirty minutes and additional time to attempt to control the temperature of the water after pouring, the volume after boiling, etc.

I did 26 tests of our device, and we didn't even do all volumes/temperatures, and our prediction was only 1° off at states. I feel like making a formula is theoretically a good idea, but in practice there are several things that could affect it (room temp, humidity, etc) so it really is better to just actually do the tests.

For a state competition, is calibrating for each 10mL worth it? Each test takes ~30 minutes and would take hours to complete everything. Or is there a way to create a cooling curve that takes both volumes of water into account (that would be pretty awesome).

[CookiePie1]

Given a cooling curve, one can (attempt to) make a formula that predicts the temperature based on time, starting temperature, and volume of water. Using this formula, one can then make a prediction. Of course, it would certainly be more effective to just use the ending temperatures, but that would require many more tests, each one taking thirty minutes and additional time to attempt to control the temperature of the water after pouring, the volume after boiling, etc.

I did 26 tests of our device, and we didn't even do all volumes/temperatures, and our prediction was only 1° off at states. I feel like making a formula is theoretically a good idea, but in practice there are several things that could affect it (room temp, humidity, etc) so it really is better to just actually do the tests.

For a state competition, is calibrating for each 10mL worth it? Each test takes ~30 minutes and would take hours to complete everything. Or is there a way to create a cooling curve that takes both volumes of water into account (that would be pretty awesome).

I didn't do every volume for ststes - I just did 50, 70, 100, 130, and 150. For the volumes in between, I just adjust predictions higher.