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xkcd #3038: Uncanceled Units (xkcd.com)

submitted 2 days ago* (last edited 2 days ago) by [email protected] to c/xkcd

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Edit: Alt Text: Speed limit c arcminutes^2 per steradian.

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[–] [email protected] 19 points 2 days ago (1 children)

No, it's because watts are joules per second, so kWh are (energy / time) * time. Cancelling the units would be expressing the energy directly in joules.

[–] [email protected] 11 points 1 day ago (2 children)

But the XKCD mentions kWh/day specifically, in theory the times can cancel out, leaving you with kW

But instantaneous and average kW are very different, and it would take more time to describe that distinction than to use kWh/day.

[–] [email protected] 1 points 1 hour ago

Ok that's fair, I kinda glossed over that part. Both are valid interpretations, I think.

[–] [email protected] 3 points 18 hours ago

My freezer was labeled in max watts, kwh/day, and kwh/year. Because the cumulative watts over time is what I pay for my power bill. That way it's a simple multiplication that tells me how much having that freezer would cost.