• qwerty@discuss.tchncs.de
    915·
    2 days ago

    I know this is a joke but if anyone is wondering it’s because they build those things to go towards the air, otherwise they would be going away from the air and it would be hard to breath. Earth is going away from the air too but luckily it has trees attached to itself that make more air and leave it behind, that’s where wind comes from.

  • mlg@lemmy.worldEnglish
    371·
    2 days ago

    I’m appalled at the amount of people in this comments section who failed elementary grade school level of physics and also somehow failed to notice this is the shitpost community

  • Worx@lemmynsfw.comEnglish
    81·
    2 days ago

    1675 + 10km/h

    1675 + 100km/h

    1675km/h

    Turns out that 1675km/h is the magic number, anything above that is dangerous

    • Idreamofcheesy@lemmy.world
      522·
      2 days ago

      Not quite. When you’re rotating, you are constantly accelerating in a tangent direction to the diameter. So the poster is right that we should be feeling a force shooting us away from the center of earth.

      Except the force of gravity cancels out the centripetal force and then some.

      So [force of gravity] - [centripetal force of Earth’s rotation] = 9.8m/s^2

      • cynar@lemmy.worldEnglish
        24·
        2 days ago

        The difference is about 0.5%. A mass weighing 100kg at the north pole would only weigh 99.5kg at the equator. Most of the difference is the centerfugal force of the earth’s rotation.

        I’ve not checked the numbers, but apparently it’s detectable in Olympic sports. More height records get broken at equatorial latitudes that higher ones.

        • tweeks@feddit.nl
          2·
          2 days ago

          Interesting, would the muscles of someone living far away from the equator be stronger in general than compared to someone with the same genes / lifestyle on the equator?

          • cynar@lemmy.worldEnglish
            5·
            2 days ago

            0.5% is so tiny that it disappears into the noise. It’s a 1 in 200 difference. In theory, it would make a difference. In practice, you won’t be able to measure it. Other confounding factors would bury it.

        • wanderer@lemmy.worldEnglish
          21·
          2 days ago

          A mass weighing 100kg at the north pole would only weigh 99.5kg at the equator

          That assumes a perfectly spherical earth. The earth is not perfectly spherical.

          • gentooer
            11·
            1 day ago

            This. Planets are in hydrostatic equilibrium, meaning that the combined acceleration by gravity and the centrifugal “force” is equal all over the world (except for local differences due to mountains and dense crust).

            • Deme@sopuli.xyz
              5·
              1 day ago

              Hydrostatic equilibrium yes, but equal? No. We agree that centrifugal force is a factor. Now ask yourself, why would gravity suddenly strengthen at the equator to get the surface acceleration to stay equal to that of the poles?

              It doesn’t. As a result the Earth seeks a new hydrostatic equilibrium, bulging out at the equator. This in turn strengthens the centrifugal force a bit while also slightly diminishing the force of gravity (because more of the planet’s mass is farther away). So the same effect is taken even further. Local differences add a layer of noise on top of this, but the end result is that the net surface acceleration is measured to average slightly less at equatorial regions than at the poles, with for example Singapore getting 9.7639 m/s2 of downward acceleration, while Helsinki gets 9.825 m/s2.

              • gentooer
                4·
                1 day ago

                You’re right, I had it backwards. Hydrostatic equilibrium makes it that the combined force vector of gravity and the centrifugal force is perpendicular to the planet surface everywhere.

      • kerrigan778@lemmy.world
        2·
        2 days ago

        Only on the equator, the force is just tiny, it produces major weather systems through the coriolis effect but only on giant scales. This would be like saying people get dizzy if they stand near the pole.

        • Idreamofcheesy@lemmy.world
          4·
          2 days ago

          It sounded like the guy meant the 1700km/h is a velocity, not an acceleration, which is why we don’t feel the force of acceleration.

          I was pointing out that spinning is acceleration, just in this case we can’t feel it due to other forces.

      • vithigar@lemmy.ca
        1·
        2 days ago

        The actual amount of centrifugal force is also tiny. Sure, it’s a relatively fast linear speed compared to something like a merry-go-round, but a merry-go-round’s angular velocity is much higher, and that’s the one you use when calculating the force trying to fling you off.

        Also, centripetal force is the inward force observed by an external non-rotating reference frame which deflects motion into a curve. You’ve conflated it with centrifugal force, which is the outward “fictitious” force experienced in a rotating reference frame.

      • db2@lemmy.world
        2·
        2 days ago

        What are those pre-math numbers though? How screwed would we be if rotation doubled or stopped (regardless of the virtual impossibility)?

        • Idreamofcheesy@lemmy.world
          8·
          2 days ago

          Have you seen the elementary school experiment where you spin an egg on a flat surface, then you stop the egg and let it go and the then the egg starts spinning again?

          If the earth suddenly stopped spinning, the atmosphere would still be spinning at 1700km/h.

          A cat 5 hurricane has wind speeds of 253km/h. So we’d be boned.

  • whotookkarl@lemmy.world
    19·
    2 days ago

    If you want to just pick the fastest velocity we can measure and we’re currently moving at thanks to dark energy the Milky Way galaxy is moving away from other distant galaxies faster than the speed of light.

  • taiyang@lemmy.world
    18·
    2 days ago

    Man, it’d be so funny if the entire atmosphere just straight up locked in place. Heck, forget rotation, have it keep it’s X/Y/Z in the universe static and just straight up disappear as our solar system moves on.

      • Wogi@lemmy.world
        3·
        2 days ago

        It’s exactly the same result! Because it’s the same scenario from different perspectives.

      • taiyang@lemmy.world
        1·
        2 days ago

        The center of the universe, I suppose. How fast is the Milky Way moving away from the center? I imagine quite fast.

        • humorlessrepost@lemmy.worldEnglish
          4·
          2 days ago

          There is no center, and there’s no fixed grid. It’s still funny to think of the atmosphere stopping from the sun’s reference frame, though.

          • taiyang@lemmy.world
            1·
            2 days ago

            Well at the very least, we’re supposedly moving 2.1million km per hour along with the Milky Way, and 720,000 km per hour within the Milky Way (so it could be more or less if that’s with Milkys movement or not), plus our own movement around our sun, so … basically really fast.

            My point is, having anything just freeze like a glitch would probably cause something terrible. Granted even relative to the sun is probably catastrophic so it’s kind of a moot point, haha.

        • Cethin@lemmy.zipEnglish
          3·
          2 days ago

          There is no “center of the universe” as far as we’re aware I’m pretty confident. We (each individual) is the center of their known/knowable universe, but that’s distinct from the actual universe. There’s stuff beyond that that we can and will never observe.

          I guess you could define the center of the universe as the average point of all matter, but since we can’t observe much of the universe we can’t know where that is.

  • Unknown1234_5@lemmy.world
    123·
    2 days ago

    Ik this is a joke but if anyone is wondering it’s because units of linear motion (km/h, mph, etc.) do not accurately describe rotation. Rotational units like rpm are much better as linear units give a misleadingly large (though technically correct) number.

    • GoodEye8@lemm.eeEnglish
      221·
      2 days ago

      If anyone is wondering it’s actually because of frame of reference. The first two images have speeds in relation to the rotation of earth, the last imagine uses a different frame of reference. If you put the last image in the same frame of reference as the first two images the number there would be 0km/h, because it would be moving in relation to itself.

      • mkwt@lemmy.world
        82·
        2 days ago

        It’s actually because the thing that makes you make those faces is the acceleration, not the speed.

        All three reference frames shown are accelerated, non inertial frames. But the first two have “fictitious” centrifugal accelerations somewhere around 0.5-2.5 g. The third frame has a detectable centrifugal acceleration, but it’s like 0.003 g or something, and can be lumped in with gravity for many types of problems.

        • beastlykings@sh.itjust.works
          11·
          2 days ago

          It’s actually because of wind resistance, the air is moving the same speed as the ground when the earth turns so you don’t feel it.

          (don’t @ me I’m just following what I recognized to be a humorous pattern of technically correct "well actually"s)

  • superkret@feddit.org
    13·
    2 days ago

    That’s cause earth isn’t actually rotating at all. The entire universe rotates around earth.

  • peanuts4life@lemmy.blahaj.zoneEnglish
    13·
    2 days ago

    Maybe my math is wrong but: The Earth’s radius is about 6,371 kilometers. With this large radius and a 24-hour rotation period, the centripetal acceleration at the equator is only about 0.034 m/s². This is tiny compared to Earth’s gravitational acceleration of 9.8 m/s². So the centripetal effect is only about 0.3% of gravity’s effect.

      • peanuts4life@lemmy.blahaj.zoneEnglish
        5·
        2 days ago

        Yes, that is the speed you’re going, then the acceleration you experience due to the change in direction as the earths surface revolves about an axis is a = v²/r. R being the radius of the earth. This gets us our small acceleration value.

        You do experience this small acceleration as a very small reduction in weight. You actually weigh more at the poles than the equator. You don’t feel the velocity at all, as the whole planet is moving with you.