Is this decent?

wxyz
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Re: Is this decent?

Post by wxyz » January 10th, 2019, 4:24 pm

C8H10N4O2! wrote:i want to ask a similar question...
I used 100 mL of water, the source temp was about 63 deg C (only 1 thermometer and did not measure too accurately). The 1st reading in the device was 57.7, which then dropped down to 50.0 after 30 minutes. The air temperature is about 19 deg C (cold house), which is a k-constant of about .00739. I'm considering building a new device with different materials, but am not sure if I will have the time due to work. Should I? If not, are there any quick ways to increase the heat retention so I can lower my k-constant (since it actually counts this year)?
You would not use 57.7 as your start water temp, you would use 63. That gives you a k-constant of -0.01167.

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Re: Is this decent?

Post by Justin72835 » January 11th, 2019, 6:00 am

wxyz wrote:
C8H10N4O2! wrote:i want to ask a similar question...
I used 100 mL of water, the source temp was about 63 deg C (only 1 thermometer and did not measure too accurately). The 1st reading in the device was 57.7, which then dropped down to 50.0 after 30 minutes. The air temperature is about 19 deg C (cold house), which is a k-constant of about .00739. I'm considering building a new device with different materials, but am not sure if I will have the time due to work. Should I? If not, are there any quick ways to increase the heat retention so I can lower my k-constant (since it actually counts this year)?
You would not use 57.7 as your start water temp, you would use 63. That gives you a k-constant of -0.01167.
The first person is right, you would use 57.7 degrees as your starting temperature. Always take the starting temperature to be the one measured right after the water is poured and the beaker is inside the device. With that said, 57.7 degrees isn't within the range of temperatures they can give, so try to make sure that your source temperature is much hotter.
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Re: Is this decent?

Post by wxyz » January 11th, 2019, 1:13 pm

Justin72835 wrote:
wxyz wrote:
C8H10N4O2! wrote:i want to ask a similar question...
I used 100 mL of water, the source temp was about 63 deg C (only 1 thermometer and did not measure too accurately). The 1st reading in the device was 57.7, which then dropped down to 50.0 after 30 minutes. The air temperature is about 19 deg C (cold house), which is a k-constant of about .00739. I'm considering building a new device with different materials, but am not sure if I will have the time due to work. Should I? If not, are there any quick ways to increase the heat retention so I can lower my k-constant (since it actually counts this year)?
You would not use 57.7 as your start water temp, you would use 63. That gives you a k-constant of -0.01167.
The first person is right, you would use 57.7 degrees as your starting temperature. Always take the starting temperature to be the one measured right after the water is poured and the beaker is inside the device. With that said, 57.7 degrees isn't within the range of temperatures they can give, so try to make sure that your source temperature is much hotter.
If that is the case, why doesn't the rules say that the supervisor will measure the initial temperature of the water in the beaker? If the score is based on the temperature measured after pouring, then you would want it to be as close to room temperature as possible.

The rules specifically state that supervisors record the source water temperature.

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Re: Is this decent?

Post by UTF-8 U+6211 U+662F » January 11th, 2019, 2:27 pm

wxyz wrote:
Justin72835 wrote:
wxyz wrote:
You would not use 57.7 as your start water temp, you would use 63. That gives you a k-constant of -0.01167.
The first person is right, you would use 57.7 degrees as your starting temperature. Always take the starting temperature to be the one measured right after the water is poured and the beaker is inside the device. With that said, 57.7 degrees isn't within the range of temperatures they can give, so try to make sure that your source temperature is much hotter.
If that is the case, why doesn't the rules say that the supervisor will measure the initial temperature of the water in the beaker? If the score is based on the temperature measured after pouring, then you would want it to be as close to room temperature as possible.

The rules specifically state that supervisors record the source water temperature.
I believe this is correct. While you should always measure the temperature after pouring in order to get an accurate prediction for the final temperature, the actual k-value for the competition will be derived from the temperature of the source bath.

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