Thermodynamics B/C

[chopchpp]

You should create a graph for every variable range you test (volume, temperature, etc.)

Actually, you could just make tables based on volume that run for about 150 mins each. This way you can use the table to predict the temperature more accurately and easily.

WAIT A MIN 150 MINS???? Explain this plz

This is all based on my assumption of what kendreaditya is trying to say, it may be totally wrong and misinterpreted

kendreaditya is saying that suppose you have a 90C beaker and you run it for the first 40 minutes. It reaches 70C (just estimating). Then you essentially have a 70C beaker that you can run for another 40 minutes (and so on and so on). This would obviously work better if you had a really good heat retention as you could test more temperature without interruption. Running for 150 minutes also ensures you cover the full time interval (20-40 min Div C)
My issue, however, with this is that in my experience, the largest drop in temperature is when the hot beaker is first placed into a room temperature box. Within the first 5 minutes, the temperatures will equilibrate (at least somewhat), the beaker quickly giving up heat to the box (Newtons law of Cooling). From there the box and beaker will continue to lose heat, but at the same temperature, and at a much slower rate. If we run something for 150 minutes, we will essential cut out the first 5 minutes where the box and beaker rapidly reach equilibrium, and as this time period is the largest temperature drop, it will greatly influence the final temperatures.
Going to the example above, upon reaching 40 minutes and having a 70C beaker, the box will also be at around 70C, thus very little heat is leaving the beaker into the box. However at competition, a 70C beaker will be placed in a room temperature box (around 24C) and it will lose around 5-8C from simply heating the box up to an equilibrium temperature. Assuming everything else is perfect, your prediction going off the 150min graph would end up significantly off the actual value.

[JonB]

Actually, you could just make tables based on volume that run for about 150 mins each. This way you can use the table to predict the temperature more accurately and easily.

WAIT A MIN 150 MINS???? Explain this plz

My issue, however, with this is that in my experience, the largest drop in temperature is when the hot beaker is first placed into a room temperature box. Within the first 5 minutes, the temperatures will equilibrate (at least somewhat), the beaker quickly giving up heat to the box (Newtons law of Cooling).

100% agree with this- well said!

[Alex-RCHS]

So how many graphs do you think are good to have?

It really varies. You may use tables instead of graphs, for one. Or, you might simply write down the functions you develop based on data and plug in variables into that function on a calculator when you get to competition. But for whatever you use -- graph, function, or table -- it's really up to you to decide how you will estimate the temperature and what you will require.

I personally will be bringing about 50-100 tables/graphs/functions to competition, but I will only use one or two there.

[Alex-RCHS]

(Sorry for the double post)

Actually, you could just make tables based on volume that run for about 150 mins each. This way you can use the table to predict the temperature more accurately and easily.

WAIT A MIN 150 MINS???? Explain this plz

This is all based on my assumption of what kendreaditya is trying to say, it may be totally wrong and misinterpreted

kendreaditya is saying that suppose you have a 90C beaker and you run it for the first 40 minutes. It reaches 70C (just estimating). Then you essentially have a 70C beaker that you can run for another 40 minutes (and so on and so on). This would obviously work better if you had a really good heat retention as you could test more temperature without interruption. Running for 150 minutes also ensures you cover the full time interval (20-40 min Div C)
My issue, however, with this is that in my experience, the largest drop in temperature is when the hot beaker is first placed into a room temperature box. Within the first 5 minutes, the temperatures will equilibrate (at least somewhat), the beaker quickly giving up heat to the box (Newtons law of Cooling). From there the box and beaker will continue to lose heat, but at the same temperature, and at a much slower rate. If we run something for 150 minutes, we will essential cut out the first 5 minutes where the box and beaker rapidly reach equilibrium, and as this time period is the largest temperature drop, it will greatly influence the final temperatures.
Going to the example above, upon reaching 40 minutes and having a 70C beaker, the box will also be at around 70C, thus very little heat is leaving the beaker into the box. However at competition, a 70C beaker will be placed in a room temperature box (around 24C) and it will lose around 5-8C from simply heating the box up to an equilibrium temperature. Assuming everything else is perfect, your prediction going off the 150min graph would end up significantly off the actual value.

To be more specific, the greater issue is the water losing heat to the beaker. That creates a very significant and not-instantaneous drop in temperature that will not be accounted for with the method described.

However, I'm not sure if that's actually what kendreaditya meant. I'm sure they will clarify soon.

[kendreaditya]

(Sorry for the double post)

WAIT A MIN 150 MINS???? Explain this plz

This is all based on my assumption of what kendreaditya is trying to say, it may be totally wrong and misinterpreted

kendreaditya is saying that suppose you have a 90C beaker and you run it for the first 40 minutes. It reaches 70C (just estimating). Then you essentially have a 70C beaker that you can run for another 40 minutes (and so on and so on). This would obviously work better if you had a really good heat retention as you could test more temperature without interruption. Running for 150 minutes also ensures you cover the full time interval (20-40 min Div C)
My issue, however, with this is that in my experience, the largest drop in temperature is when the hot beaker is first placed into a room temperature box. Within the first 5 minutes, the temperatures will equilibrate (at least somewhat), the beaker quickly giving up heat to the box (Newtons law of Cooling). From there the box and beaker will continue to lose heat, but at the same temperature, and at a much slower rate. If we run something for 150 minutes, we will essential cut out the first 5 minutes where the box and beaker rapidly reach equilibrium, and as this time period is the largest temperature drop, it will greatly influence the final temperatures.
Going to the example above, upon reaching 40 minutes and having a 70C beaker, the box will also be at around 70C, thus very little heat is leaving the beaker into the box. However at competition, a 70C beaker will be placed in a room temperature box (around 24C) and it will lose around 5-8C from simply heating the box up to an equilibrium temperature. Assuming everything else is perfect, your prediction going off the 150min graph would end up significantly off the actual value.

To be more specific, the greater issue is the water losing heat to the beaker. That creates a very significant and not-instantaneous drop in temperature that will not be accounted for with the method described.

However, I'm not sure if that's actually what kendreaditya meant. I'm sure they will clarify soon.

Sorry for the late response, think you got what I meant. However, on the last part, I was confused about how my prediction would be off. Since the probe that I use to measure the temperature of the beaker can collect data every second an create a table out of it, I just make the table a .csv, upload it to my calculator, and theirs my data. But at competitions, the given temperature always changes since heat is lost to the beaker. So I use the probe to measure the starting temperature of the beaker, then I see the corresponding time say at 28 min (in my data table on my calc). Then I add the time given at competition (for example, 40 min, 30 min, 25 min...in this case assume 30 min) and see the corresponding temperature data value for the minute, which will be 58 min.

I am really bad at explaining things!

This is an example dataset thats on my calc:

https://nofile.io/f/zQwTH4DArkt/Capture3.PNG

[kendreaditya]

So how many graphs do you think are good to have?

It really varies. You may use tables instead of graphs, for one. Or, you might simply write down the functions you develop based on data and plug in variables into that function on a calculator when you get to competition. But for whatever you use -- graph, function, or table -- it's really up to you to decide how you will estimate the temperature and what you will require.

I personally will be bringing about 50-100 tables/graphs/functions to competition, but I will only use one or two there.

Lol, I only bring 1 table with around 5,000 data points, 1,000 for each water volume

[IDon'tKnowMyName]

This is kind of off topic, but in the rules it says that the length to height ratio of your two identical beakers must be about 1.4.

We've only found beakers that have length to height ratios of about 1.2. Would you say that this is something to worry about or are the event supervisors just looking to see if you if your beaker looks normal and isn't a mutilated beaker with a length to height of 3?

[kendreaditya]

This is kind of off topic, but in the rules it says that the length to height ratio of your two identical beakers must be about 1.4.

We've only found beakers that have length to height ratios of about 1.2. Would you say that this is something to worry about or are the event supervisors just looking to see if you if your beaker looks normal and isn't a mutilated beaker with a length to height of 3?

Should be fine, but I am not from Colorado so...

[WhatScience?]

This is kind of off topic, but in the rules it says that the length to height ratio of your two identical beakers must be about 1.4.

We've only found beakers that have length to height ratios of about 1.2. Would you say that this is something to worry about or are the event supervisors just looking to see if you if your beaker looks normal and isn't a mutilated beaker with a length to height of 3?

Should be fine, but I am not from Colorado so...

I dont think that they will measure your beaker. I'll let yall know how thermo is run at NJ states after tomorrow.

[TheChiScientist]

I agree as they only want a standard beaker and not some crazy modified one.