Comment on Little Pea Shooters

• absGeekNZ@lemmy.nz ⁨2⁩ ⁨days⁩ ago

  No, it’s hard to explain without diagrams.

  But as you fall towards a planet (any gravity well); you pick up speed, if the planet is moving away from you, you fall for longer before you catch up. As you climb back up, you don’t spend all of the energy you gained on the way down. That difference is the Slingshot effect.

  It also works in reverse, if the planet is moving towards you. You catch up quicker, thus gain less speed. And spend overall more energy than you gained when you climb back out. Slowing down in the process.

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  • kuberoot@discuss.tchncs.de ⁨2⁩ ⁨days⁩ ago

    I’m confused, but this doesn’t make sense to me.

    It shouldn’t matter whether you’re moving in the same direction or not for this, because ultimately it’s all relative - if you set the planet as the frame of reference, the direction you come in from doesn’t matter - just the velocity and angle.

    What I can see working is calculating the in and out angles - if the exit velocity is at a sharper angle relative to the planets velocity than the entrance angle, then your exit velocity “gains” more of the planet’s velocity than the entrance velocity “loses”.

    If you were completely stationary, from the planet’s point of reference, you’re moving with the velocity of the planet. If you then did half an orbit, exiting in the other direction (theoretically), from the planet’s point of reference you have the same speed, just in the other direction - but from the sun’s point of reference, you’re now moving at the planet’s speed on top of the planet’s own speed, thus gaining double the velocity of the planet.

    The issue is, of course, I have no idea if I’m making sense, or missing the point.

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    • deaf_fish@midwest.social ⁨2⁩ ⁨days⁩ ago

      As others have said, you are stealing kinetic energy from the planet to go faster. Or giving kinetic energy back to the planet to go slower.

      So, relatively, you slow down and the planet speeds up or the planet slows down and you speed up.

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      • kuberoot@discuss.tchncs.de ⁨2⁩ ⁨days⁩ ago

        Right, but as I explained, it’s the how that doesn’t make sense to me - the explanation that you “fall for longer” doesn’t make sense, since 1. with how orbits work, it takes the same energy and time to “fall” as it does to ascend, and 2. at these scales you can use the planet as an inertial frame of reference, so the angle of approach doesn’t matter for how “long” you “fall”, it’ll be the same regardless of whether you’re moving towards or away from the planet.

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    • Batman@lemmy.world ⁨2⁩ ⁨days⁩ ago

      your taking advantage of the planets immense kinetic energy.

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    • agroqirax@lemmy.world ⁨2⁩ ⁨days⁩ ago

      This explains it quite nicely: youtube.com/shorts/kD8PFhj_a8s

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      • kuberoot@discuss.tchncs.de ⁨2⁩ ⁨days⁩ ago

        Ayy, I’m not crazy, that sounds like exactly what I described… The only question is, is the explanation of “you spend longer falling” is bs, or if it makes sense if you conceptualize it differently?

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