• whotookkarl@lemmy.world
    link
    fedilink
    arrow-up
    8
    ·
    2 hours 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
    link
    fedilink
    arrow-up
    11
    ·
    5 hours 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.

    • Idreamofcheesy@lemmy.world
      link
      fedilink
      arrow-up
      23
      ·
      5 hours 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.world
        link
        fedilink
        English
        arrow-up
        10
        ·
        4 hours 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
          link
          fedilink
          arrow-up
          1
          ·
          2 hours 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.world
            link
            fedilink
            English
            arrow-up
            1
            ·
            22 minutes 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.

        • Idreamofcheesy@lemmy.world
          link
          fedilink
          arrow-up
          3
          ·
          4 hours 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.

      • db2@lemmy.world
        link
        fedilink
        arrow-up
        2
        ·
        5 hours 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
          link
          fedilink
          arrow-up
          6
          ·
          4 hours 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.

  • Worx@lemmynsfw.com
    link
    fedilink
    English
    arrow-up
    35
    ·
    7 hours ago

    1675 + 10km/h

    1675 + 100km/h

    1675km/h

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

  • Unknown1234_5@lemmy.world
    link
    fedilink
    arrow-up
    2
    arrow-down
    2
    ·
    2 hours 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.ee
      link
      fedilink
      English
      arrow-up
      8
      ·
      1 hour 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
        link
        fedilink
        arrow-up
        2
        arrow-down
        1
        ·
        54 minutes 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
          link
          fedilink
          arrow-up
          2
          ·
          39 minutes 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
    link
    fedilink
    arrow-up
    7
    ·
    6 hours ago

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

  • peanuts4life@lemmy.blahaj.zone
    link
    fedilink
    English
    arrow-up
    8
    ·
    6 hours 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.zone
        link
        fedilink
        English
        arrow-up
        1
        ·
        edit-2
        3 hours 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.