• Captain Aggravated
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    263 months ago

    Fun fact: in aviation, a “standard day” at sea level is defined as 29.92 inches of mercury of pressure an 15°C in temperature, and San Francisco is a coastal town so it’s near as makes no odds to sea level.

    15°C is basically the most average temperature on Earth.

    • Dharma Curious (he/him)
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      83 months ago

      Why is it defined in inches and centigrade? Why not inches and fahrenheit or cm and centigrade? Mixing systems hurts my brain :(

      • @[email protected]
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        73 months ago

        Mercury would typically be measured in mm in metric and my brain just fully glossed over the inches part

        • Dharma Curious (he/him)
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          43 months ago

          I don’t know why it bugs me so much, but whenever I see mixed units it really does. It’s like my brain itches or something.

          Also, yeah, mm makes more sense.

          • Captain Aggravated
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            43 months ago

            You ever hear the expression “Fahrenheit is how humans feel, Celsius is how water feels?” Pilots in flight are concerned with how water feels, so we use Celsius.

            My favorite “mixed” unit has to be the standard adiabatic lapse rate, which is 2°C per thousand feet. 1000 feet above your head right now it’s 2 degrees Celsius cooler than it is at your altitude. You can use this along with the current surface temperature and dewpoint to determine things like where clouds and icing will form.

            The one that gets me is speeds and distances are usually expressed in nautical miles/knots, while visibility is expressed in statute miles.

            • shrugs
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              23 months ago

              Nice read. I find it really interesting that due to the unwillingness of many to learn something new, America is almost the only country that still uses these silly measurements.

              5280 ft in a mile my ass. You don’t even use 0.x numbers but fractions like 7/8th instead. And still some people believe that 1/4 pounder is bigger then a 1/3 pounder. That’s crazy

              • Captain Aggravated
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                13 months ago

                I’m on the record as genuinely preferring fractional inches to decimal units in the wood shop because it’s inherently a fractional task. 12 inches in a foot; keep dividing that by two and you get 6", 3", 1 1/2", 3/4", 3/8" and so on. 3/4" is the basic unit of woodworking. I have to divide by two and three quite a lot in the wood shop, so dividing 3/4" by three is 1/4" Easy.

                Did this today: I had a 1 1/2" thick board, and had to cut a 1/2" groove down the center of that board. 1 1/2 divided by three is 1/2" so I chucked a 1/2" spiral bit in my router, set the fence 1/2" from the bit and the grooves are perfectly centered. Easy.

                I’m not against the metric system, I learned chemistry and physics in metric, I own a set of metric wrenches. My measuring cups are graduated in fractional cups and milliliters, my kitchen scale measures in ounces, pounds and grams. But I build furniture in fractional inches and I learned to fly a plane in feet, pounds, gallons and nautical miles, and I’m damn good at both.