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The bowling ball isn’t falling to the earth faster. The higher perceived acceleration is due to the earth falling toward the bowling ball.

  • Shard@lemmy.world
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    3 months ago

    So will the bowling ball gravitationally attract the earth to itself there by reach the earth an infinitesimally small amount?

    • BB84@mander.xyzOP
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      3 months ago

      Yes, the earth accelerates toward the ball faster than it does toward the feather.

        • BB84@mander.xyzOP
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          3 months ago

          If your bowling ball is twice as massive, the force between it and earth will be twice as strong. But the ball’s mass will also be twice as large, so the ball’s acceleration will remain the same. This is why g=9.81m/s^2 is the same for every object on earth.

          But the earth’s acceleration would not remain the same. The force doubles, but the mass of earth remains constant, so the acceleration of earth doubles.

          • Venator@lemmy.nz
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            3 months ago

            I wonder how many frames per… picosecond you’d need to capture that on camera… And what zoom level you’d need to see it.

            I think the roughness of the surface of the bowling ball would have a bigger impact on the time, in that the surface might be closer at some points if it were to rotate while falling.

            • WhatAmLemmy@lemmy.world
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              3 months ago

              Considering the mass of the earth (?) moon, I wouldn’t be surprised if it’d be nearly impossible to capture a difference between a feather or bowling ball. You might have to release them at 100m or 1000m above the surface, but then maybe the moons miniscule atmosphere or density variances will have more of an effect.

          • Robust Mirror@aussie.zone
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            3 months ago

            But if you’re dropping them at the same time right next to each other, the earth is so large they would functionally be one object and pull the earth at the same combined acceleration.

  • reliv3@lemmy.world
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    3 months ago

    This argument is deeply flawed when applying classical Newtonian physics. You have two issues:

    1. Acceleration of a system is caused by a sum of forces or a net force, not individual forces. To claim that the Earth accelerates differently due to two different forces is an incorrect application of Newton’s second law. If you drop a bowling and feather in a vacuum, then both the feather and the bowling ball will be pulling on the Earth simultaneously. The Earth’s acceleration would be the same towards both the bowling ball and the feather, because we would consider both the force of the feather on the Earth and the force of the bowling ball on the Earth when calculating the acceleration of the Earth.
    2. You present this notion that two different systems can accelerate at 9.81 m/s/s towards Earth according to an observer standing on the surface of Earth; but when you place an observer on either surface of the two systems, Earth is accelerating at a different rate. This is classically impossible. If two systems are accelerating at 9.81 m/s/s towards Earth, then Earth must be accelerating 9.81 m/s/s towards both systems too.
    • BB84@mander.xyzOP
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      3 months ago

      Re your first point: I was imagining doing the two experiments separately. But even if you do them at the same time, as long as you don’t put the two objects right on top of each other, the earth’s acceleration would still be slanted toward the ball, making the ball hit the ground very very slightly sooner.

      Re your second point: The object would be accelerating in the direction of earth. The 9.81m/s/s is with respect to an inertial reference frame (say the center of mass frame). The earth is also accelerating in the direction of the object at some acceleration with respect to the inertial reference frame.

      • Trail@lemmy.world
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        3 months ago

        If the earth would be accelerating towards you, then g would be less than 9.81.

        Think of free falling, where your experienced g would be 0.

      • reliv3@lemmy.world
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        3 months ago

        Even if you imagine doing them separately, the acceleration of the Earth cannot be calculated based on just a singular force unless you assume nothing else is exerting a force on the Earth during the process of the fall. For a realistic model, this is a bad assumption. The Earth is a massive system which interacts with a lot of different systems. The one tiny force exerted on it by either the feather or bowling ball has no measurable effect on the motion of Earth. This is not just a mass issue, it’s the fact that Earth’s free body diagram would be full of Force Vectors and only one of them would either be the feather or bowling ball as they fall.

        As for my second point, I understand your model and I am defining these references frames by talking about where an observer is located. An observer standing still on Earth would measure the acceleration of the feather or bowling ball to be 9.81 m/s/s. If we placed a camera on the feather or bowling ball during the fall, then it would also measure the acceleration of the Earth to be 9.81 m/s/s. There is no classical way that these two observers would disagree with each other in the magnitudes of the acceleration.

        Think of a simpler example. A person driving a car towards someone standing at a stop sign. If the car is moving 20 mph towards the pedestrian, then in the perspective of the car’s driver, the pedestrian is moving 20 mph towards them. There is no classical way that these two speeds will be different.

        • BB84@mander.xyzOP
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          3 months ago

          Earth is in this case not an inertial reference frame. If you want to apply Newton’s second law you must go to an inertial reference frame. The 9.81m/s/s is relative to that frame, not to earth.

    • Xavienth@lemmygrad.ml
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      3 months ago

      The difference in relative acceleration implied by the meme is on the order of tens of yoctometres (10⁻²³ m) per second per second.

      It’s a difference so small that it would be overshadowed by the fact that you’re holding one object femtometres (10⁻¹⁵ m) higher or lower than the other in the gravitational field.

      Additional sources of error to consider at this scale might be the heat radiation from the surroundings providing radiation pressure on the object, the sloshing of Earth’s core causing time-dependent variations in the gravitational field, the location-dependent variations in the Earth’s gravitational field, and the difference in centrifugal (yes, centrifugal in this reference frame) force due to latitude differences of one micrometre, and also due to natural variations in the rate of Earth’s rotation over time.

    • KyuubiNoKitsune@lemmy.blahaj.zone
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      3 months ago

      I love it when scientists who know something to be true in theory get to see practical experiments like this. The jubilation on thier faces.

  • CatZoomies@lemmy.world
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    3 months ago

    There’s too many words in this meme that’s making me dizzy from all your fancy science leechcraft, wizard.

    I reject your reality and substitute my own: the feather falls faster. It’s more streamlined than the bowling ball, and thus it slips through the vacuum much faster and does hit the ground and stay on the ground, I think. The ball will bounce at least once, maybe even three times. On each bounce, parts of it probably break off, which change the weight. Thankfully those broken pieces won’t hurt anyone because they’re sucked up by the vacuum. Thus, rendering your dungeon wizard spells ineffective against me.