• Thunderwolf@lemmy.world
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    7 months ago

    There are people that think this post is wrong because the equation is wrong or due to a lack of units

    The equation for cylindrical volume is correct (circular area multipled by height).

    And the units are unimportant (can be described as cubed units)

    The issue is that Pi is a constant. Constants and variables are different things.

    Other examples of constants: 1, 24, 7, -1 … Etc.

    Saying Pi = 5 is like saying 1 = 5 … Both Pi and numbers like 1,2,3, etc. have a constant (non-varying) value.

    You can’t reassign a value on a constant. It’s like me sticking up 3 fingers and claiming there are 5 fingers there.

    • CameronDev@programming.dev
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      7 months ago

      For the purpose of teaching young school kids how to substitute real values for constants/variables, does it matter? π is a constant, but the value you use for it in exams and real life will not be the same, or the actual correct value. Getting students used to the idea that even constants can have varying values in exams or software is useful.

      In my exams π had values ranging from 3, 3.1 to whatever the calculator had. g also ranged from 9.8 to 10, although in fairness g is not a constant.

      At least setting it to 5 can spark debate around what a more reasonable approximation should be.

      • new_guy@lemmy.world
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        7 months ago

        OP’s problem isn’t even wrong.

        It’s just assuming that π is 5 in this specific scenario, just like it’s reasonable to assume the existence of a spherical cow in a frictionless environment. Yeah, if you use the results of this problem to develop a real cylinder you’re going to have a bad time but nobody is doing that all what’s the problem?

        Nobody is saying that from this point in time and going forward π = 5 and now math is broken forever. People need to chill