• untorquer@lemmy.worldEnglish
    3·
    3 days ago

    Are we simply to assume the donuts have a homogenous internal structure? Clearly there’s not enough information.

  • KoboldCoterie@pawb.socialEnglish
    3·
    6 days ago

    Obviously the left one.

    In physics, the center of mass of a distribution of mass in space is the unique point at any given time where the weighted relative position of the distributed mass sums to zero. For a rigid body containing its center of mass, this is the point to which a force may be applied to cause a linear acceleration without an angular acceleration.

    If they wanted this to be an actual, debatable question, they shouldn’t have used ‘center of mass’, as the term has a specific definition and the question has a correct answer; it’s not open to interpretation, like “How would a horse wear pants?” or similar questions.

  • DannyBoy@sh.itjust.worksEnglish
    2·
    6 days ago

    In high school we were taught if the center of mass wasn’t on any mass then the center of mass was “virtual”. But yes the center of mass doesn’t have to exist on the object.

    • Kongar@lemmy.dbzer0.comEnglish
      2·
      6 days ago

      Not saying you’re wrong - you’re probably right. But as an engineer, I’ve referred to or been asked about “the center of mass” thousands of times and not once have I ever heard “virtual” used. It’s just always the center of mass - wherever that point exists in all of spacetime.

      It’s weird. Did something change over the years (like using the Oxford comma or double spacing after a period?). Or is that something that’s always been a thing that I’ve never run across? Strange ;)

  • BreadOven@lemmy.worldEnglish
    0·
    6 days ago

    The secret third option: looking at the picture on the left; going straight through the donut through the middle in the vertical direction.

    Although now that I saw it, I still think the original left picture is the correct answer. Even through the middle vertically as I mentioned, the centre of gravity would be the same, would it not?

    • WolfLink@sh.itjust.worksEnglish
      2·
      6 days ago

      Left is correct. The center of mass of a donut is inside the hole, which is “outside the donut”.

      This may seem unintuitive, but the center of mass of an object does not have to be inside the object.

      This is the mechanism behind these toys:

      The wings of the bird and poles of the clown extend below the main body, but are weighted so that’s where most of the weight is. So the center of mass is below the main body, so it will easily balance on the main body. However, your eyes will naturally focus on the main body, which would be unstable without the extra weight hanging off the side, making the balancing look surprising.