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   Wolfe Silver (wolfe@terrible.city)'s status on Sunday, 24-Mar-2024 12:52:49 JST Wolfe Silver

   every once in a while i think about how furlongs-per-pint is exactly the same as miles per gallon

   • Haelwenn /элвэн/ :triskell: repeated this.
   • Embed this notice
     Wolfe Silver (wolfe@terrible.city)'s status on Sunday, 24-Mar-2024 12:52:47 JST Wolfe Silver

     in reply to

     furlong = an eighth of a mile

     pint = a half of a quart
     = a half of (a quarter gallon)
     = an eighth of a gallon

     furlongs per pint = (eighths of a mile) per (an eighth of a gallon)

     cancelling out like terms we get

     furlongs per pint = miles per gallon

   • Embed this notice
     Wolfe Silver (wolfe@terrible.city)'s status on Sunday, 24-Mar-2024 12:54:01 JST Wolfe Silver

     in reply to

     looking forward to when i start driving electric cars and need to incorporate watts and joules and newtons into my calculations

     Haelwenn /элвэн/ :triskell: likes this.
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     Wolfe Silver (wolfe@terrible.city)'s status on Sunday, 24-Mar-2024 12:54:03 JST Wolfe Silver

     in reply to

     suppose you're driving a car that uses 11 liters of fuel for every 100 km

     11 liters per 100 km = 11,000 cm cubed per 10,000,000 cm
     = 0.0011 cm cubed per cm

     i.e. for every centimeter that the car inches forward, uh, i mean, centimeters forward, it needs 0.0011 cubic centimeters of fuel

     if we need to give our car 0.0011 cubic centimeters of fuel every time it drives forward one centimeter, then a pipe with a cross-section of 0.0011 **square** centimeters would exactly do the trick, so long as the fuel inches forward exactly one centimeter every time the car does

     i.e. fuel flows into the engine at the same speed that the car drives forward, and the pipe we're using to fuel the engine has a cross-sectional area of 0.0011 cm squared

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     Wolfe Silver (wolfe@terrible.city)'s status on Sunday, 24-Mar-2024 12:54:04 JST Wolfe Silver

     in reply to

     sure it's nice to be all mathematical and create this wacky unit, but what does "my car has a fuel efficiency of 0.0011 square centimeters" mean in the real world?

     if we were to pump fuel directly into the engine, with fuel flowing in at the same speed that the car is going, then our fuel pipe would need a cross-sectional area of 0.0011 square centimeters

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     Wolfe Silver (wolfe@terrible.city)'s status on Sunday, 24-Mar-2024 12:54:05 JST Wolfe Silver

     in reply to

     in europe, the efficiency of cars is measured in liters-per-100km

     liter per 100km = 1000 cubic cm per 10,000,000 cm
     = 1 cubic cm per 10,000 cm
     = 1/10,000 cm squared

     which is in fact a unit of area

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     Wolfe Silver (wolfe@terrible.city)'s status on Sunday, 24-Mar-2024 12:54:07 JST Wolfe Silver

     in reply to

     i wasn't even the one who discovered this, but i don't remember who did (and mastodon basically doesn't have search, so i'll never know)

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     Haelwenn /элвэн/ :triskell: (lanodan@queer.hacktivis.me)'s status on Sunday, 24-Mar-2024 12:54:55 JST Haelwenn /элвэн/ :triskell:

     in reply to
     @wolfe In fact https://what-if.xkcd.com/11/ illustrates this.