Thermodynamics B/C

[JoeyC]

Make sure to label! (almost lost points on that soon)

[RishithR]

Does K stay constant with a specific box?

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

Does K stay constant with a specific box?

More or less

[CookiePie1]

Does K stay constant with a specific box?

More or less

Not really - devices don't retain heat as well when volumes are altered, so k-values for lower volumes are generally worse than those for higher volumes. k-values should only be compared within their own volume ranges.

[builder83]

Just making sure I am getting my chart score perfect after reading this thread. I want to submit 4 or more time vs temp charts that can include 1 or more data series with 10 different temp readings per series. Label with units.

Also include a labeled picture diagram of box.

Question 2: Do you include a data series like at 56 or 58 degrees? (Assuming a 60 degree bath is used and the heat loss before I take my first reading.) Similarily do you bother with 75 degrees? (Division B)

[Crimesolver]

Just making sure I am getting my chart score perfect after reading this thread. I want to submit 4 or more time vs temp charts that can include 1 or more data series with 10 different temp readings per series. Label with units.

Also include a labeled picture diagram of box.

Question 2: Do you include a data series like at 56 or 58 degrees? (Assuming a 60 degree bath is used and the heat loss before I take my first reading.) Similarily do you bother with 75 degrees? (Division B)

Is the first one a question or a clarification?????? Yeah those are the parameters. To your second question, yes. You have to start whenever the thermometer hits the water and start timing from there. For 75 degrees, you would just heat the water to 75 degrees, then pour it in the beaker and measure for how long you need to.

[Crimesolver]

Heat Score (HS) = 20 x (lowest k of all teams)(the k value closest to zero of all teams) / k, where k is from Newton’s law of cooling: k = - (1 / cooling time) x ln((start water temp - room temp) / (final water temp - room temp))

Has anyone noticed this clarification? Just figured this out today. Does anyone know if recent competitions have been using this questions instead of the previous one?

[chalker]

Heat Score (HS) = 20 x (lowest k of all teams)(the k value closest to zero of all teams) / k, where k is from Newton’s law of cooling: k = - (1 / cooling time) x ln((start water temp - room temp) / (final water temp - room temp))

Has anyone noticed this clarification? Just figured this out today. Does anyone know if recent competitions have been using this questions instead of the previous one?

This doesn't really impact anything. The official spreadsheet was already calculating this correctly. We previously said 'smallest', but due to the fact k is negative smallest technically is 'most negative'. However, anyone running the event would obviously know the objective it to retain the MOST heat, not LOSE the most heat, which is what you'd have to do to get a really large negative k value.

[JoeyC]

Yeah, as long as the ES's know how the k value correlates with heat retention, it should be fine.

[mjcox2000]

It seems to me like it's not an issue of retaining vs. losing heat, but rather an issue of the range of scores. Supposing the worst team had a k of 1.0 and the best had a k of 0.01: under the rules as written, the worst team would get 20 points and the best team 2,000, while the clarification makes it so the worst team gets 0.2 points and the best team 20. In both cases, the best team gets more points and the worst team gets fewer. It's just a question of whether scores should be in the range (0 .. 20) or the range (20 .. infinity).