> good luck with that... electrical power engineering speaks in kWh not MJ
Then it's industry-specific jargon. Note that some places bill your natural gas consumption in megajoules. Food energy is quoted in kilojoules in SI, or calorie/Calorie/kilocalorie otherwise.
The problem is that if you want to make any comparisons, you need to use the same units.
An athlete eats 100 Calories, gets on an exercise bike, and powers a 100-watt light bulb for 3000 seconds. What is her thermodynamic efficiency?
To make the 500 km journey, the old car consumed 1 GJ worth of heat energy in gasoline. The new electric car consumed 300 kW⋅h. Which one consumed less energy?
> Particle physicists will hate you if you take electron volts from them
I can understand why they love their traditional unit of measurement.
The problem is that their unit measures the same type of quantity (energy) as an existing SI unit - the joule.
We've seen this play out in countless industries already, where they have their own specific units and refuse to interoperate.
Heating in BTUs, cooling in tons, explosions in kilotons of TNT, barrels of oil.
Astronomy in light-years or parsecs or astronomical units, typesetting in points, football in yards (instead of feet), microscopic things constantly compared to the width of a human hair, ~5 different scales of shoe sizes across the world.
> it is incorrect to attach letters or other symbols to the unit in order to provide information about the quantity or its conditions of measurement
I agree with this rule. I guess if you write it out in words, it would be:
Then it's industry-specific jargon. Note that some places bill your natural gas consumption in megajoules. Food energy is quoted in kilojoules in SI, or calorie/Calorie/kilocalorie otherwise.
The problem is that if you want to make any comparisons, you need to use the same units.
An athlete eats 100 Calories, gets on an exercise bike, and powers a 100-watt light bulb for 3000 seconds. What is her thermodynamic efficiency?
To make the 500 km journey, the old car consumed 1 GJ worth of heat energy in gasoline. The new electric car consumed 300 kW⋅h. Which one consumed less energy?
> Particle physicists will hate you if you take electron volts from them
I can understand why they love their traditional unit of measurement.
The problem is that their unit measures the same type of quantity (energy) as an existing SI unit - the joule.
We've seen this play out in countless industries already, where they have their own specific units and refuse to interoperate.
Heating in BTUs, cooling in tons, explosions in kilotons of TNT, barrels of oil.
Astronomy in light-years or parsecs or astronomical units, typesetting in points, football in yards (instead of feet), microscopic things constantly compared to the width of a human hair, ~5 different scales of shoe sizes across the world.
> it is incorrect to attach letters or other symbols to the unit in order to provide information about the quantity or its conditions of measurement
I agree with this rule. I guess if you write it out in words, it would be:
* Incorrect: "Power: 480 volt-amps-reactive (VAR)"
* Correct: "Power (reactive): 480 volt-amps (V⋅A)"
* Correct: "Reactive power: 480 volt-amps (V⋅A)"
By the way, you can link to a specific page like this: https://physics.nist.gov/cuu/pdf/sp811.pdf#page=16