• Zerush@lemmy.ml
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    22 hours ago

    With same gravity constance everything fall down at the same speed, but only in a vacuum. In an atmosphere there count the air resistance of an object, even if they are made of the same material and weight, an iron sphere of 1 kg fall faster than a iron sheet of 1 kg.

      • falcunculus@jlai.lu
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        18 hours ago

        I assume you mean keeping the outer diameter the same and making one ball lighter than the other. That’s clever, it would eliminate aerodynamism as a factor.

        However wouldn’t results still vary, since hollowing out the metal ball increases its buoyancy ? (Archimedes’ principle).

        • heatofignition@lemmy.world
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          16 hours ago

          They would have the same coefficient of drag, correct, but the air resistance would end up having more effect on the lighter mass of the hollow sphere, so it would be slightly slower to fall.

          Archimedes principle here is accounted for in the different weights. Everything that you can put on a scale is already being acted on by Archimedes principle in air.

    • ryannathans@aussie.zone
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      9 hours ago

      Except if you could measure exactly the speed of objects falling in a vacuum, the heavier object would appear to fall faster due to the gravitational pull on the Earth. You’re forgetting the Earth falls toward the object too.

      • Zerush@lemmy.ml
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        18 hours ago

        No, mass or weight of an object is irrelevant, in one of the jurney to the Moon, astronauts demostrate it with an hammer and a feather on the moon that both fellt at the same speed. It exist one gravity aceleration, on earth is 9,82 ms², which is the force of acceleration which experiment any object on Earth, the only difference which can slow it down is the resistant of air, this can be different in each object, but without atmosphere there is nothing which slow down the acceleration of the object, it’s irrelevant the material, weight, mass or form. Basic physic

        https://www.youtube.com/watch?v=Oo8TaPVsn9Y

        • ryannathans@aussie.zone
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          9 hours ago

          The difference is far too small to measure at these scales, the Earth would be falling toward the more massive object faster than the less massive object. Therefore the more massive object hits first.

        • heatofignition@lemmy.world
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          16 hours ago

          R^2 is on the bottom. We don’t ignore the mass of one object because it’s insignificant, that would make the top of that equation 0 and the object wouldn’t fall at all.

          That nifty gravitational law gives you the force of gravity on an object, not the acceleration. Force also equals mass times the resultant acceleration, right? So Fg1 = m1*A1 = G*M*m1/r^2 and Fg2 = m2*A2 = G*M*m2/r^2. m1 and m2 are present on both sides of those equations, respectively, so they cancel, and you get A1 = G*M/r^2 and A2 = G*M/r^2, which are identical. The mass of an object affects the force of gravity, but when you look at acceleration the mass terms cancel out.