ssManae said:
Tumedus said:
ssManae said:
Tumedus said:
Beyond the movie just looking dull to me, one scene that I keep seeing just ruins the appeal for me: When she detaches from the spinning arm, she flies backward and the arm continues forward. Horrible horrible physics. In space, detaching would have almost no impact on her previous trajectory, she would continue rotating with the arm, just no longer bound to it.
It may seem like a nitpick, but for a movie entirely about the experience of falling to earth from outer space, things like that just rub me the wrong way.
That's completely opposite of what would happen. When she detaches herself from the arm, there is no longer a centripetal force. From the arm's frame of reference, she'd be flung away like throwing a discus. With the camera following the arm, and her releasing at the right moment, what they show is exactly what would happen.
I think you should watch the trailer again. The discus analogy, while not perfect, is pretty apt. And that is the problem as it doesn't accurately reflect that in the video.
When she detaches she should travel outward from the rotating arm (centrifugal force), following the same directional vector it is on (shared velocity) and only spinning opposite to the rotation of the arm if you believe she rolls off of it (I can forgive this part as her feet are shown as attached even though she only appears to unhook a waist harness) . In other words, from our point of view, she would be traveling outward from the arm but remain perfectly in line with its center of rotation because all other velocities would remain the same.
But in the scene she actually changes velocity as she moves away from the arm and doesn't rotate along the same axis as the arm (even if you accept the opposite spin).
These issues are particularly bad if you trace it all the way back to the detachment from the shuttle as there are a few problems with that part as well.
I think I'm seeing the actual problem now. First, the camera does not keep attached to a fixed frame of reference. It releases from the one it was following when she does. Second, you're misunderstanding centrifugal forces. She will not go flying out from it, she'll fly out tangentially on a perfect release. On a perfect release, she would continue in her current direction at the speed of the center of mass, plus the rotational speed times the radius from the center of mass. Finally, the center of mass is not the center of the arm. This further skews the direction she appears to be traveling as the long end continues spinning towards the camera.
There are some wonky physics for sure, but her disconnecting is not the worst of it.
I don't know maybe I am not explaining it well because you keep telling me I don't understand stuff I thought I was already explaining. Although looking at the first post, I said she would "rotate with the arm" which was a poor choice of words and maybe why you think I don't know what I am saying.
So in the interest of clarity let's fix some terms. Centrifugal force technically has no bearing on her direction at all once she releases from the arm. Inertia is what determines her velocity. That is why, on a perfect release, she would move tangential to the spin at the moment of release. On an imperfect release (going with the discus analogy) the vector, while still technically tangential to the initial release point, would appear to radiate outward from the spinning object and cause the opposite spin on the released object.
The camera does change a lot, but we can still see where we are in relation to the spin of the arm. And since we continue to see the spin after she has released, it is clear she moves in the opposite direction of the tangent relative to the arm. The most appropriate direction for her to move in that scene would have been down out of frame. Depending on how much additional rotation you give the disconnect for the discus analogy, you could argue some angle between down and toward the camera. The only justifiable way to have her move up out of frame would be if the camera continued to follow her previous anchor point, but it clearly does not.
At any rate, you seem to know your physics, even if you believe I don't, and have acknowledged that there are bad physics in the scene so I will leave it there. That specific point just struck me because of her blatant change of velocity when she releases from the arm. Not sure, given everything you just said, why you still think the scene is okay, but its no big.
The movie still looks rather uninteresting.
Edit: and the more I think about the scene, her harnessed pivot point off of the arm is almost definitely below her center of gravity, which is on the leading edge of the rotation. So the discus analogy doesn't really work for her spin since a discus is thrown with the grip behind the leading edge. She should be spinning with the same rotation as the arm if any spin at all. That may have added to my dissonance, even if I hadn't rationalized it before, but it wasn't part of my initial complaint.
