Why are Watt Hours not Watts per Hour? Are they the same thing?
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Think about a big tank of water.
Now imagine I hook a hose up to it and let water drain out for an hour.
The hose is “a thing that lets water out at a specific rate”. The water that drained is “how much water that hose let out in an hour”.
Watts are like the hose. They’re how much energy gets spent per unit time. But if I asked you “how many hoses per hour does this bigger pipe drain?” that question is weird, because we want “amount of water” not “amount of hoses”.
Same thing with Watts. It says “this much energy moves per unit time”. There’s already a “per time” in it. So if you divide by time again, things get weird.
What makes more sense is “If this pipe drains as fast as 2 hoses, how much water do I get if it is open for 3 hours?” Each hose let out “1 hose-hour” per hour, so this pipe (2 hoses) multiplied by 3 hours drains 6 hose-hours of water in 3 hours. (The answer will be even weirder due to gravity and some other Physics but that’s another story.)
That’s the real trick. The phrase “per hour” means DIVIDE by time. But a Watt-hour is what you get if you MULTIPLY Watts by time.
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