• mlg@lemmy.world
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    1 month 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.com
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    1 month 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
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      1 month 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
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        1 month 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.

        • wanderer@lemmy.world
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          1 month 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@programming.dev
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            1 month 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
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              1 month 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@programming.dev
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                1 month 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.

        • tweeks@feddit.nl
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          1 month 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
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            1 month 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.

      • kerrigan778@lemmy.world
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        1 month 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.

      • db2@lemmy.world
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        1 month 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
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          1 month 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.

        • Idreamofcheesy@lemmy.world
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          1 month 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.

  • peanuts4life@lemmy.blahaj.zone
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    1 month 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
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        1 month 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.

  • superkret@feddit.org
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    1 month ago

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

  • datendefekt@lemmy.ml
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    1 month ago

    You see, that is another perfect example for why earth has to be flat, anything else just isn’t logical!

  • qwerty@discuss.tchncs.de
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    1 month 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.

  • taiyang@lemmy.world
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    1 month 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.

      • taiyang@lemmy.world
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        1 month 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.world
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          1 month 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.

        • Cethin@lemmy.zip
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          1 month 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.

      • Wogi@lemmy.world
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        1 month ago

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