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Old 10-17-2012, 10:05 AM   #101
anthonyk
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Originally Posted by Homeslice View Post
I just want to make sure what it is we're disagreeing about. Are you saying that if you took 2 guys, both of them jumping from the same altitude, but one is doing it within the normal atmosphere while the other is doing it inside some kind of vacuum tube, that the first guy would feel the jump while the other wouldn't?
They would both feel the same initial sensation of falling or weightlessness. For the guy in the vacuum, that would persist. For the one in the atmosphere, he'd slowly transition back to "weighted" as air resistance started slowing his acceleration.
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Old 10-17-2012, 10:33 PM   #102
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You're right except that in free fall in a vacuum where you have absolutely no forces acting on your at all the molecules in your body are going to fall at the same rate as yoru space suit or as if you were made out of solid steel. Everything falls at the same rate in a vacuum. If for some magical reason your stomach fell at say 9.80 meters per second per second and the rest of your body fell at 9.81 meters per second per second then you'd feel your stomach because your stomach would exert a force against your nerves which are trying to travel at a different velocity.

When you jump out of an airplane you are immediately subject to the affects of air resistance and pressure, like it or not. So in a sense, inside your body your guts want to fall at 9.81m/ss but due to air resistance you are actually falling at 9.70m/ss. Because of that you have a net Force and no matter how small a force, something with mass will experience acceleration.
This right here makes sense.
As for your vector post with arrows & shit, I only comprehended the first two-thirds of it. Sorry.
But this post right here makes sense.
So, I can see how air resistance would cause a difference in acceleration between your body and your guts, until terminal velocity is reached.
I would still argue that the initial shift from weighted to weightlessness is something anyone could feel, because as soon as you step off that platform, suddenly there is no force being exerted on your feet, knees, hips, back, neck, etc. Of course, that feeling would probably cease after a split second, so maybe Felix chose not to bother mentioning it, because it was so trivial when compared to the lack of freefalling sensation caused by the lack of air pressure.

Last edited by Homeslice; 10-18-2012 at 12:44 PM..
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Old 10-17-2012, 10:42 PM   #103
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In space, if you jet yourself one way for just a moment, you will just keep accelerating with nothing to cause friction to slow you down, but you don't feel it at all.
Correction, you would keep accelerating only while the engine was on. When you shut it off, you would remain at the same velocity forever, unless disturbed.

Also, when you say "you don't feel it", I disagree, because your back would be pressed into the seat when you hit go. In fact that's the biggest BS about sci-fi movies, next to the noise in space issue.

Last edited by Homeslice; 10-18-2012 at 12:43 PM..
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Old 10-18-2012, 04:30 PM   #104
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I would still argue that the initial shift from weighted to weightlessness is something anyone could feel, because as soon as you step off that platform, suddenly there is no force being exerted on your feet, knees, hips, back, neck, etc. Of course, that feeling would probably cease after a split second, so maybe Felix chose not to bother mentioning it, because it was so trivial when compared to the lack of freefalling sensation caused by the lack of air pressure.
I don't know the actual feeling he would get. If there is one I doubt it's detectable by him. Mathematically, the moment his feet left the platform he wouldn't feel anything. Even his guts if they were amplified.

As you stated, correctly, about how once hte rocket turns off you are at a constant velocity with no acceleration (though technically I think you could say you are accelerating at 0 meters per second for every second), it's the same for your feet. If Felix jumped straight up, the absolute time, 1/(infinity) of a second, instantly in the true sense of instant, he is subject to the acceleration of gravity due to earth. It's illogical to think about but that is how it must work. Except at the quantam level.

Or say he shot himself straight up out of a cannon. Assume once he leaves the barrel, there isn't anymore force on him. If he was shot out with a velocity of 1million mph, he would feel he stopped right outside the barrell and wouldn't know when his velocity went to 0 or when he started coming back to earth (providing he has no reference points).

As for the scifi stuff. I don't watch too much science fiction stuff, but I think they've adopted now the warping of space*time where that stuff isn't a concern.
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Old 10-18-2012, 04:46 PM   #105
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I don't know the actual feeling he would get.
Sure was a long journey to reach that conclusion.

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...you are at a constant velocity with no acceleration (though technically I think you could say you are accelerating at 0 meters per second for every second)
Have you ever heard someone try SO hard to speak authoratively and/or make things more complicated than they really are, only to lose credibility?
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Old 10-18-2012, 07:31 PM   #106
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Have you ever heard someone try SO hard to speak authoratively and/or make things more complicated than they really are, only to lose credibility?
Except when it comes to math and science I am very smart. Plus, I enjoy teaching people this stuff because it helps me. I give skype lesson's to my friend's daughters for their school work. Well, schoolwork that involves math or science. They're screwed if they have grammer or spelling questions.

I'm also very passionate about space travel. Anytime someone has interest in math, physics, chemistry, etc. I really jump on it. It's just on TWFix I try and do it in a more douchebag uppity fashion. People don't respond well to politeness on here.
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Old 10-18-2012, 11:11 PM   #107
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This went from a cool thread to the most boring thread in the world.
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Old 10-19-2012, 02:07 AM   #108
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(though technically I think you could say you are accelerating at 0 meters per second for every second
Finally I understand why the seconds are squared. Been so many years since school that I forgot that shit. Its talking about a velocity increase of X mps every second. So, if the acceleration was 5 mpss, then the velocity would be 5 mps after the first second, 10 after the second, and so on.

But what if the rate of accel is increasing, how would you express that in one number?
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Old 10-19-2012, 10:52 AM   #109
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Originally Posted by Smittie61984 View Post
Except when it comes to math and science I am very smart. Plus, I enjoy teaching people this stuff because it helps me. I give skype lesson's to my friend's daughters for their school work. Well, schoolwork that involves math or science. They're screwed if they have grammer or spelling questions.

I'm also very passionate about space travel. Anytime someone has interest in math, physics, chemistry, etc. I really jump on it. It's just on TWFix I try and do it in a more douchebag uppity fashion. People don't respond well to politeness on here.
Skype lessons, huh?

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Old 10-19-2012, 12:20 PM   #110
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Skype lessons, huh?

Funny, that's what I read too
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