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Comment by grondilu | Hacker News Reader

Not related, but I hate this unit. Can't we just talk about Joules?

It's not pretty,but it's practical. Especially when it comes to electricity - watts and hours are quite easy to work with.

Perhaps, but it makes conversion to and from an other domain than electricity a pain.

It doesn't make much difference whether you use Watts or Joules, since 1 Watt = 1 Joule per second, so both are just as convenient for electricity: 1 Watt = 1 Volt Amp, so 1 Joule = 1 Volt Amp Second = 1 Volt Coulomb (although amps seems to be more "normal" than coulombs).

It's a bit redundant to multiply power by time, when that's just an energy, but going between Watts and Joules is trivial (by design), so it's not too bad.

However, I can't think of a reason why hours would be easier to work with than seconds (as kiloseconds, if you want the same order of magnitude), especially regarding electricity?

It's because power needs are reported as watts, and impactful devices are typically utilized for several hours. It's much easier to do your monthly utilization napkin math in multiples of kilowatt-hours than of 3.6 megajoules.

I'm personally not a fan of the kWh, because it keeps being mistaken for kW, but I recognize that lack of need for a conversion factor help a lot of people make sense of energy.

Joules are tiny it takes 3.6 million Joules = 1kWh

SI prefixes FTW.

1kWh = 3.6 MJ

Yep - my natural gas bill is denoted in MJ.

That has the opposite problem a 3.6 TJ per hour powerplant = 1 GW. Aka 1billion joules per second * 1 hour / 1 hour.

Might as well just say 1 billion joules per second aka 1 GW then tack on or remove an hour if needed.

I don't think they were proposing using J per time as a unit for power, just for power instead of using W * time.

Watt-hours are tiny, it takes 1 thousand Watt-hours = 1kWh ;)

My personal favorite is the quad: one quadrillion British thermal units of energy. It's used for whole-planet and large-nation scales of energy per year.

Same here.

1 kWh = 1 joule hour per second

How does it make sense to have 2 different units of time in there?

"How does it make sense to have 2 different units of time in there?"

This way it's easier to calculate how much energy your appliances uses. For example, if your vacuum cleaner is 1000W (1kW), running it for an hour will use 1kWh of energy which cost you can clearly see on your electricity bill. Unless you also want to re-lable all appliances, electric engines etc. in joules.. Sure, joule makes much more sense in physical calculations.

Horsepower ftw

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