OK, this is dumb, but it's gone through my head a couple times. I've seen a few science fiction movies and shows where the people in the spaceship use a gravity assist and lean into the turns like they're driving NASCAR or riding a roller coaster.

I think they wouldn't feel the acceleration (vector change) because gravity is doing the acceleration on every molecule and there would be nothing to lean against. I'm often wrong though. Someone smarter than I am have some insight?

EDIT: For what it's worth, I guess I shouldn't have used the Expanse clip as it upset some people. I just used it for an example of what I was asking. The question is this: Under little or no thrusters, would you feel a gravity assist? Even a radical one that changes your direction 90 degrees and greatly increases your velocity?

  • RedAggroBest@lemmy.world
    26·
    1 year ago

    Gravity is why people lean into turns in the first place.

    Those molecules have velocity that's taking them past whatever body they're using for a gravity assist. The gravity of that body grabs the vessel and begins to pull it in, being pulled closer to the body generating that acceleration and not simply passing by. The previous vector doesn't just disappear. All that matters still wants to continue in that direction of travel, including the people. The result is people having to lean into the arc of the assist because their own momentum is still changing to the new vector.

    In short. Inertia is a bitch

    • Pons_Aelius@kbin.social
      3·
      1 year ago

      I am not so sure.

      In a gravity assist ( to be technical using a hyperbolic orbit of a large mass to change direction and gain velocity) the object is still following the curvature of space time. So the change in direction is affecting all particles in the object at the same time. There is no external force involve, so inertia does not come into play.

      It is the same as people in the ISS orbiting the earth, they do not have to lean in the curve as they are following the curvature in spacetime around the planet. The only difference is one is a hyperbolic orbit (gravity assist) while the other is a parabolic elliptical orbit (ISS)

      While the analogy the OP used of leaning into a turn is changing direction and there is a force that is only acting on part of the object (the tires of a car or motorbike).

    • ℛ𝒶𝓋ℯ𝓃@pawb.social
      31·
      1 year ago

      Only one problem - the relative velocity of the ship is the same. Yes, the ship's vector got changed, but yours did too. Same reason you don't feel centripetal force in orbit, despite the constant vector change at 9.8m/s^2…

    • Bytemeister@lemmy.worldΕλληνικά
      2·
      1 year ago

      There is a miniscule amount of tidal forces felt during a gravity assist. Ultimately, the spacecraft and it's cargo are in freefall. The gravity assist would be barely noticeable. Remember that gravity isn't a "force" it's a bending of space changing the direction of a "straight " path. The spacecraft is traveling in a straight line with no other forces acting on it. The space that straight line is passing through is bent around the mass providing the gravity assist.