Comment on The SAT Question Everyone Got Wrong

• protist@mander.xyz ⁨10⁩ ⁨months⁩ ago

  I summarized it above, there’s an extra rotation included when the outer circle moves along the inner circle, essentially falling a bit with every roll forward. If the outer circle rolled along a straight line of the same length as the circumference of the inner circle, it would only roll 3 times, but moving around the circle instead adds exactly one extra rotation. That other gent says this is used in calculating orbits too, where you’re also moving forward while constantly falling

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  • SpaceNoodle@lemmy.world ⁨10⁩ ⁨months⁩ ago

    I read an article about it. Everybody is doing a shit job of describing what happens. The outer circle naturally makes a full rotation as it travels around the inner one, as the path it follows goes around a full 360°, so that counts as one of the rotations it ends up making, which is in addition to the 3 due to travel around the circumference.

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    • OmnislashIsACloudApp@lemmy.world ⁨9⁩ ⁨months⁩ ago

      thank you, that was the comment that explained it for me

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      • SpaceNoodle@lemmy.world ⁨9⁩ ⁨months⁩ ago

        Thanks for letting me know! It was too frustrating to not share.

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• schmidtster@lemmy.world ⁨10⁩ ⁨months⁩ ago

  Add the radius together. If the circle is inside. A-B 3-1 = 2.

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  • protist@mander.xyz ⁨10⁩ ⁨months⁩ ago

    Does not compute

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    • schmidtster@lemmy.world ⁨10⁩ ⁨months⁩ ago

      It’s in the video.

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      • protist@mander.xyz ⁨10⁩ ⁨months⁩ ago

        First you said add the radii together, then you gave an example subtracting them, but either way this is incorrect. You divide the larger radius by the smaller radius and add 1

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      • uphillbothways@kbin.social ⁨10⁩ ⁨months⁩ ago

        Not quite. With radius 2 and 3 circles, the outer circle would take 2.5 rotations to complete the revolution. You have to set the first circle radius to 1 and then add the radii to calculate the relative circumference of the circle drawn by the motion of the center of the outer circle, so the answer would be calculated like:

        2/2 + 3/2 = 5/2 = 2.5

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  • SpaceNoodle@lemmy.world ⁨10⁩ ⁨months⁩ ago

    [deleted]

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    • schmidtster@lemmy.world ⁨10⁩ ⁨months⁩ ago

      …?

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      • bisby@lemmy.world ⁨10⁩ ⁨months⁩ ago

        Its not even remotely what you said. Its A/B+1 or A/B-1 for an interior loop.

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