• missingno@fedia.io
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    10 hours ago

    When accounting for air resistance, heavy objects do fall faster than light ones. They couldn’t test in a vacuum back then, they only knew how things work here in Earth’s atmosphere.

    • Frezik@lemmy.blahaj.zone
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      9 hours ago

      A similar size chunk of iron and coal would have done the experiment just fine. Any two objects of the same shape and size but significantly different densities.

      • missingno@fedia.io
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        9 hours ago

        If two objects have the same size and shape, the force applied by air resistance will be the same. However, if two objects have different mass, that same force will result in different acceleration.

        • psud@aussie.zone
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          7 hours ago

          The acceleration will be 1G minus drag. The Earth is sufficiently larger than anything one would drop off a tower so the weight of the dropped thing doesn’t matter at all

          How does your model of the universe explain the hammer and feather dropped on the moon by Apollo 15’s David Scott landed at the same time?

          Ed. There is an effect of buoyancy that will make denser things fall faster. It becomes noticeable in distances where the dropped items reach terminal velocity or on more dense media where buoyancy is more significant.

          In air over short distances buoyancy is negligible, in vacuum there is none

          • missingno@fedia.io
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            7 hours ago

            minus drag

            On Earth, this is the part that makes it so that objects do not fall at the same speed.

            on the moon

            This is the type of experiment they could not do 2000 years ago.

            • psud@aussie.zone
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              4 hours ago

              minus drag

              On Earth, this is the part that makes it so that objects do not fall at the same speed.

              That is incorrect. Drag affects both equally. The difference is caused by buoyancy, less dense objects feel more buoyancy

              • Rivalarrival@lemmy.today
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                3 hours ago

                Buoyancy is functionally irrelevant here. Buoyancy in air effectively subtracts 1.3kg per cubic meter of each substance: The mass of the volume of air displaced by the object.

                The part you are not understanding: Drag applies the same force to both objects. Gravity applies the same acceleration to each object.

          • mnemonicmonkeys@sh.itjust.works
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            7 hours ago

            The Earth is sufficiently larger than anything one would drop off a tower that the weight of the dropped thing doesn’t matter at all

            F=ma.

            Two items of the same shape will have the same amount of air resistance. If they have significantly different masses, the two object experience commensurately different accelerations (or reduction in acceleration), even if the force is the same.

            If you take a balloon full of tetrahexofluroride (a gas 6x the density of air) and a chunk of iron the exact same size and shape and throw them off a building, I guarantee the iron chunk will hit first.

            How does your model of the universe explain the hammer and feather dropped on the moon by Apollo 15’s David Scott landed at the same time?

            It’s called a vacuum, which is famous for not having air resistance. Y’know, the thing we’re talking about?

            To perform the experiment properly on Earth where there is air resistance, you need to pick a shape and range of masses that minimize the effect of air resistance

          • Rivalarrival@lemmy.today
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            7 hours ago

            Read their claim again: they are specifically describing the effect of air resistance. Their claim is perfectly consistent with the lunar feather/hammer experiment.

            • psud@aussie.zone
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              4 hours ago

              Their problem was that they weren’t able to say why, and no one replying to me was able to do more than say they’re right, I’m wrong. See my edit. I added a correction after looking up drag equations for myself and finding that buoyancy was a factor

              Also, thank you for replying civilly

              • Rivalarrival@lemmy.today
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                3 hours ago

                They did. You didn’t understand what they said.

                Two items of the same shape will have the same amount of air resistance. If they have significantly different masses, the two object experience commensurately different accelerations (or reduction in acceleration), even if the force is the same.

                The “same force” they are talking about is drag. The two objects are the same size and shape. At the same velocity, drag affects them both equally, applying an equal, upward force against both objects.

                Gravity (in a vacuum) accelerates both objects equally. But they have differing masses. F=MA. F/M = A. A is equal for both objects. Because acceleration is equal, the “force” on each object is not: the force must be proportional to its mass: The high mass object must be experiencing high force; the low-mass object must be experiencing low force.

                Subtract the “same force” of drag from the downward force on both objects, and the net force on each object is no longer proportional to the mass of each object. Consequently, the high-mass object accelerates in atmosphere faster than the low-mass object. The high-mass object has a higher terminal velocity; the low-mass object has a lower terminal velocity.

                For the purposes of this experiment, buoyancy is functionally irrelevant. The effect of buoyancy is to subtract a fixed mass from each object: A mass equivalent to the mass of air displaced by the object. Effectively, buoyancy slightly reduces the density of both objects. The actual difference in the densities of the two objects is far greater than the slight change due to buoyancy in air, so buoyancy is not a significant factor.

        • StellarExtract@lemmy.zip
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          8 hours ago

          While that is true, two properly selected objects (such as the ones mentioned above) can reduce the effect of air resistance to levels negligible to human perception, demonstrating that heavier objects do not intrinsically fall faster.

          • ColeSloth@discuss.tchncs.de
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            7 hours ago

            Not at all. Our air is made up of physical objects (molecules of oxygen and nitrogen, mostly). Things with more mass, more quickly knock those out of the way.

            For a demonstration you can see and more easily wrap your head around, take something just barely heavier than water, and a similarly sized heavy rock and drop them in a pool. You’ll see how much quicker the rock gets to the bottom, because it displaces the water so much faster. Our atmosphere is the exact same.

          • psud@aussie.zone
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            7 hours ago

            The difference is the different buoyancy of the balls in air. That’s negligible.

    • waigl@lemmy.world
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      9 hours ago

      Nope, denser objects fall faster than less dense ones (through the air). Remember: A kilogram of feathers is just as heavy as a kilogram of lead.

      • PastafARRian@lemmy.dbzer0.com
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        55 minutes ago

        Not really true, it’s definitely possible for a less dense object to fall faster than a denser one. A drop of water will fall faster than a parachute made of nylon, which will fast much faster than a glider plane made of metal.

      • mnemonicmonkeys@sh.itjust.works
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        7 hours ago

        Nope, denser objects fall faster than less dense ones (through the air).

        Technically it’s objects with a higher mass-to-drag ratio, but most of the time it’s close enough