Comment on Banana for scale

• SwingingTheLamp@piefed.zip ⁨4⁩ ⁨hours⁩ ago

  Okay, then, how much energy does it take to boil 1mL of water from room temperature? (Note that I said “boil,” not raise it to 100°C.)

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  • GreyEyedGhost@piefed.ca ⁨4⁩ ⁨hours⁩ ago

    We will assume that room temperature is 20° C. The heat of enthalpy is 2257 kJ/kg, or 2.257 kJ/g. As stated previously, the amount of energy to raise water 1 degree is 1 cal, which also equals 4.184 J. So,

    (100-20) × 4.184 + 2257 = 80 × 4.184 + 2257 = 334.72 + 2257 = 2592 J rounded to the nearest whole number. This will leave you with a dry pot.

    Now show me the process using Fahrenheit, fluid ounces, and foot-pounds.

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    • SwingingTheLamp@piefed.zip ⁨3⁩ ⁨hours⁩ ago

      It’s about 1 BTU per fluid ounce per degree Fahrenheit, so:

      128 fl oz × (212 - 68)°F × 1BTU/fl oz•°F = 18,432 BTU

      Add in the enthalpy of vaporization:

      7.5 BTU/fl oz × 128 fl oz = 960 BTU

      So, about 19,392 BTU.

      I’m cooking pasta for dinner, and I didn’t do any calculations. I just put the water in the pot on the stove, and waited for it to boil. Which was kind of the point of my question. Metric is all neat and elegant, but that’s irrelevant in daily life, because if I did have to calculate the energy requirement, I’d have to look up the enthalpy value, because it’s not memorable, as well as figuring in the actual atmospheric pressure to determine the actual boiling temperature. It makes all the sense in the world to use SI where it matters (e.g. science experiments), but customary units persist because in so much of daily life, it doesn’t matter.

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      • GreyEyedGhost@piefed.ca ⁨1⁩ ⁨hour⁩ ago

        So your argument is we don’t need this in everyday life. Sure, that’s sort of true, but I guarantee this was necessary in making a stove that would work in your area. But also true is that if it doesn’t matter that much in day-to-day life, then the only reason to keep such a clunky system is familiarity.

        Also, 1 BTU is the amount of energy to raise the temperature of 1 pound of water 1 degree F. So your calculations are already off by a factor of 128. Given the world doesn’t need you to know the numbers for water to boil, that doesn’t affect much, but perhaps the vastly higher number for heating the water versus the amount of energy to get the water to vaporize should have clued you in that something was weird. It’s easy to tell in metric because most of the dimensional conversion values are 1 or factors of 10.

        There are people who like to dismiss the value of knowledge because it isn’t important in their daily lives. This is only true if you live in a hut where the only sources of force are human, animal, or fire, or there is someone unseen that you rely on who has used those tools extensively to provide you a life where knowing that isnt necessary. Raising the bar with ridiculous conversion calculations every step of the way makes understanding these concepts more difficult for the layperson and makes the field harder to enter.

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