This fogs my brain every time I watch one of these shows and I feel like maybe I’m completely misunderstanding the physics.
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You’re in a “ring” ship. The ring spins. You’re standing on the inside of the ring so it takes you along with it, and the force created “pins” you to the floor, like a carnival ride. Ok, fine.
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But that’s not gravity, and it’s not “down”. Gravity is acceleration, so what keeps the acceleration going in the ring ship is that you are constantly changing your angular momentum because you’re going in a circle. Ok, so when you let go of something, like a cup or a book, wouldn’t it go flying towards the floor at an angle? If you jumped wouldn’t you look like you rotated a little before you hit the ground, because you’d, for that moment, be continuing the momentum of your angular velocity from when you left the floor and the room would continue on it’s new, ever turning, course?
Wouldn’t it kind of feel like walking “uphill” one direction and “downhill” the other, with things sliding about as the room “changed” direction constantly?
Am I just COMPLETELY missing this idea and creating a cause and effect that doesn’t exist?
In: Physics
This is one reason why you need a fairly large radius for the rotating habitat, to minimise Coriolis effects. Otherwise these effects would be pronounced and it would be VERY disorienting.
If you were on a spinning ship and dropped something it would land at your feet on a ring ship.
It is all about frame of reference, if you are standing inside the right holding a hammer. You, the ring, the hammer and the air are stationary to each other.
The centripetal force is pushing you into the floor acting like gravity. If you let go of the hammer it is still moving sideways at the same speed as you and the ring so it will fall down to your feet.
In a smaller ring you may notice some sideways movement but this is because you are inside a circle and there is a difference of speed between the centre of the ring and the outside edge
Tom Scott visited a test room that spins like that. Check it out. https://youtu.be/bJ_seXo-Enc?si=j-niDobaX7b_BF-8
Cool side note, the force you’re correctly imagining was first devised by monks trying to disprove the theory that Earth was a curved, rotating globe. They correctly posited that cannonballs would appear to curve in flight – an effect that must be accounted for with all long-range artillery. It’s named for the first guy who took it seriously, Coriolis.
If they ‘drop’ something then that object is no longer experiencing any forces.
As such it will continue in a straight line…which intersects with the floor eventually. As the object moves in a straight line, you are also swept sideways by the rotation (that you had with the object) so that when the object connects with the floor your feet are there as well.
Significant changes in height can cause odd trajectories. The object held aloft in a spinning ring is actually moving with the same angular speed, but a lower linear velocity. this means that as it moves ‘down’ it’s lower speed will cause it to be left behind by the faster moving ‘lower’ objects closer to the rim.
So instead of seeing it fall straight down, it’ll drift or curve ‘back’. Likewise any object thrown up will curve ‘forward’ as it starts with a higher velocity near the rim, compared to any objects closer to the axis.
In large rotating objects this won’t be to noticeable, as the change in radius from a persons head to feet is small compared to the overall radius of the spinning structure. But small enough structures, or large enough falls would create a noticeable effect.
You might enjoy this video from one my favourite channels on physics and space: https://youtu.be/b3D7QlMVa5s?si=oRzCh5g6PAGpdhDi that covers this topic in a lot of detail (while still managing to not make me feel stupid)
The spinning thing needs to be moving in a large enough circle to minimize that effect….
The reason that Miller pours the booze sideways in that scene from the Expanse is that he’s in the ‘slum’ part of the station close to the center (the fact that he knows to do this points to him growing up down below)…..
There is also the problem that your head experiences less gravity than your feet, and the predictions are that this will feel super weird
In those sci-fi shows where ships spin to create gravity, it’s kind of like being on a spinning ride at the fair. When you’re inside the spinning part of the ship, it pushes you against the floor, making it feel like gravity.
Now, when you drop something, it does move outward at first because of the spinning, but since everything inside the ship is also moving with it, the object ends up falling straight down, just like on Earth.
And if you jump, yeah, you might rotate a bit before landing, but because the spinning is consistent, it feels pretty smooth, like being on a rotating platform. So, it’s not gravity, but it sure feels like it.
When you hold something, it moves with you. When you let it go, it is free to move in the direction it was moving just the moment you let it go. When ship spins, it constantly changes the direction of travel of everything that is held by the inner surface, by the friction against inner surface, or is held by anyone on inner surface. So when you let go of something, it doesn’t just “fall”, it simply keeps going in the direction it was already moving, but the floor of the ship is in the way.
Note, the object wouldn’t actually fall straight down, it follows a curve path due to the difference of velocity between the ship inner surface and the object, because the object you’re holding would be closer to the center of the ship (called the Coriolis effect), so the smaller the ship, the more curved the fall path is. On much smaller ships, the dropped object won’t land at your feet, but fall somewhat sideways.
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