Thermodynamics B/C Build

[lianasv]

hmm, yesterday at the COBRA invitational in MI, they left the thermometer in the beaker for the whole 25 min when measuring the temperature. Is that allowed since the heat is escaping my device by the thermometer??

There's a statement in the rules in section 4.f. saying that they can do this, but it they must announce that they are doing so before impound.

weird, they didn't say anything in impound.

[builder83]

It was discussed how not to get your beaker stuck when using spray foam. If I am understanding the rules correctly, can you make it so your beaker is stuck in the foam as long as there is access to the top?

[Creationist127]

It was discussed how not to get your beaker stuck when using spray foam. If I am understanding the rules correctly, can you make it so your beaker is stuck in the foam as long as there is access to the top?

3.c (emphasis added): "Within the device, participants must be able to insert and remove a beaker that they supply."
So, no. Besides, if you did that, putting the water in might splash your device, which, depending on your materials, could be bad for the device.

[builder83]

I also assume it is pretty common practice to take your own temp reading after water has been given by ES? This can be done after bringing device back to table in the first 3 minutes? Thanks in advance

[JoeyC]

Yes. Always do this as somewhere in the transfer of the water to your beaker the temperature has already drooped~3-5*C.

[CPScienceDude]

Yes. Always do this as somewhere in the transfer of the water to your beaker the temperature has already drooped~3-5*C.

I’d say that’s a little generous. I always loose around 8*C when pouring water into the beaker.

[as1092]

Hi guys,
So it's my second year on thermodynamics and last year I did pretty well on thermo. For reference here's the equation for my build's prediction last year, usually, it was 1-3 Degrees off at most.

Final Temp = 25 + (Initial temp - 25)e^ ((0.0000848(v) -0.0212)t)
t= time, v = volume (mL)

I used aerogel thermal wrapping inside and used Styrofoam for the actual box. Most attachments were done with hot glue/ ducktape.
So, I really want to make my build even better this year and a lot of the new rules I know are going to help make it better, but does anyone have any suggestions?
Thanks                                                                                                                                                                                              

There's always a way to make things better. If you want, you can try gluing your device together with a stronger, more permanent adhesive. Since you have a whole season ahead of you, you could even try dabbling with vacuums and such. You can be really creative. Test-wise, you could learn more material and history. There's always something you can do to make it better.

Hey! How did you come up with that equation. Right now, our graphs are simply the temperature in relation to the time at specific volumes. How do combine all the data points up for multiple trials to get one equation?

[CPScienceDude]

Hi guys,
So it's my second year on thermodynamics and last year I did pretty well on thermo. For reference here's the equation for my build's prediction last year, usually, it was 1-3 Degrees off at most.

Final Temp = 25 + (Initial temp - 25)e^ ((0.0000848(v) -0.0212)t)
t= time, v = volume (mL)

I used aerogel thermal wrapping inside and used Styrofoam for the actual box. Most attachments were done with hot glue/ ducktape.
So, I really want to make my build even better this year and a lot of the new rules I know are going to help make it better, but does anyone have any suggestions?
Thanks                                                                                                                                                                                              

There's always a way to make things better. If you want, you can try gluing your device together with a stronger, more permanent adhesive. Since you have a whole season ahead of you, you could even try dabbling with vacuums and such. You can be really creative. Test-wise, you could learn more material and history. There's always something you can do to make it better.

Hey! How did you come up with that equation. Right now, our graphs are simply the temperature in relation to the time at specific volumes. How do combine all the data points up for multiple trials to get one equation?

I too, would love to get some insight on this. Right now I just use multiple trails to find the average heat retention of my device (78%) and multiply the source bath temp by that number.

[CookiePie1]

There's always a way to make things better. If you want, you can try gluing your device together with a stronger, more permanent adhesive. Since you have a whole season ahead of you, you could even try dabbling with vacuums and such. You can be really creative. Test-wise, you could learn more material and history. There's always something you can do to make it better.

Hey! How did you come up with that equation. Right now, our graphs are simply the temperature in relation to the time at specific volumes. How do combine all the data points up for multiple trials to get one equation?

I too, would love to get some insight on this. Right now I just use multiple trails to find the average heat retention of my device (78%) and multiply the source bath temp by that number.

I'm pretty sure the equations people use are just based off of Newton's Law of Cooling. However, I wouldn't really reccomend basing predictions off of an equation because we don't live in an idealized world, and it's overall more accurate to just take enough trials to be able to predict for a given temperature, volume, and time.

[geniusjohn5]

So let me get this straight: for the building portion of the event, do I just construct a small box made out of heat resistant material (styrofoam, cardboard, etc.) and that's it?