Aces High Bulletin Board
General Forums => The O' Club => Topic started by: cav58d on November 04, 2005, 12:07:34 AM
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Okay this is prolly a stupid question...But hey, no question asked is stupid right?
Okay now in space there is zero gravity as we all know....
Now say the shuttle is cruising straight and level, and proceeds to abruptly pitch nose down....What happens? nothing right? since there is zero G, they would not get the feeling of negative gravity like pitching the nose of an aircraft down....
wow i must sound like an idiot
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in space, no one can hear you anyway.
if something caused the shuttle to pitch abruptly, in the absence of a countering force, it will continue to pitch 360 degrees, over and over; done quickly and long enough this will generate sufficient centrifugal forces to create...
artificial gravity.
duh.
:cool:
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Originally posted by cav58d
Okay this is prolly a stupid question...But hey, no question asked is stupid right?
Okay now in space there is zero gravity as we all know....
Now say the shuttle is cruising straight and level, and proceeds to abruptly pitch nose down....What happens? nothing right? since there is zero G, they would not get the feeling of negative gravity like pitching the nose of an aircraft down....
You feel G forces because of inertia and inertia is depended on mass not the gravity.
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Originally posted by cav58d
Okay now in space there is zero gravity as we all know....
Now say the shuttle is cruising straight and level, and proceeds to abruptly pitch nose down....What happens? nothing right? since there is zero G, they would not get the feeling of negative gravity like pitching the nose of an aircraft down....
No, they would feel nothing. If they were near a gravitational feild, like near the sun, then probably a bit of a jolt.
But anyway, you must remeber that in space there's no such thing as down. Which is why that movie 'Wing Commander' sux bcuz he said that he'd go vertical to shake the bandit of his tail, but he forgot that in space there's no such thing as up!
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G forces have nothing to do with gravity at all. G is just the unit used and is equal to the gravitional force at Earths surface. If you suddenly change direction that means you must have been acted on by a force and you will feel that force. So in your example if the Shuttles thrusters fired so as to pitch the Shuttle up you would feel a downward force (positive Gs) if you were in the cockpit (and if you were strapped in) and you would feel a negative G or upward force if you were on the tail. (But that would be the least of your worries as there is no air at that end) The force you 'feel' is your own inertia counteracting the applied force; at the nose you are pushed downward into your seat because your body doesn't want to move and the seat is being pushed up against it by the thrusters.
Newtons laws and all.
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Nasa uses Newton.
Newton works in space.
G force works in space.
Centrifugal force works in space.
Take a loop in space and you will feel your own weight.
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Originally posted by Naytch
No, they would feel nothing. If they were near a gravitational feild, like near the sun, then probably a bit of a jolt.
But anyway, you must remeber that in space there's no such thing as down. Which is why that movie 'Wing Commander' sux bcuz he said that he'd go vertical to shake the bandit of his tail, but he forgot that in space there's no such thing as up!
dont mean to be a pain, but actually there is always an up and down for an object with mass, and a defined 'right side up' and 'bottom side down' configuration. eg: person, space craft, apple.
despite there being no dimmensions in space, you can still term your movements of your own personal horizontal and vertical axis.
now i feel smart!
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I have to say this is one of the most inteligent threads on this board in a long time :) Keep it up. :P
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True, but then it'd be regarded as upWARD or downWARD, not up or down.
Up and down is used in general directions e.g. up is the direction pointing towards the sky, and down towards the ground. Now, with that in mind, imagine you were lying down on your belly, looking at the ceiling. Even though the sky is still directly in front of you, it is still regarded as "up".
But since there's no such thing as sky or ground in space, then you talk about directions RELATIVE to the object of mass, and then it does not remain up or down, but a suffix of -WARD is added to denote direction relative to the object of mass.
Let's say you were in a space suit and an asteroid was above your head. You would say that it was above you, and that you would have to turn upWARDS to face it.
Now if you were in a plane in the atmosphere and a bandit was above you, you'd say it was above you, but you'd only need to pull UP to face it, understand?
Now I feel smart :D
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You watched 'Wing Commander':rofl
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Biggest waste of time EVAR!!!
Uhh, wait...
whut?
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dang, now i feel like you're smart and im not so smart :(
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Originally posted by Naytch
. Which is why that movie 'Wing Commander' sux bcuz he said that he'd go vertical to shake the bandit of his tail, but he forgot that in space there's no such thing as up!
That's neither the beginning nor the end of why that movie sucks.
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"That's neither the beginning nor the end of why that movie sucks."
The real reason for the motion picture suckage would be the fact that the games (Wing Commander 3 and 4) had both a better plot and better actors than the Hollywood POS.
"since there is zero G, they would not get the feeling of negative gravity like pitching the nose of an aircraft down...."
That feeling of "negative gravity" isn't caused by gravity at all; it's caused by inertia. Inertia works perfectly fine in deep space so you'd still feel it. Actually, given the extreme velocities objects in space move at, if a ship "abruptly" changes its vector the occupants would likely be injured or die because of the extreme forces. This is why most science-fiction spaceships are described as having some sort of "inertial dampers".
J_A_B
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Originally posted by cav58d
Okay this is prolly a stupid question...But hey, no question asked is stupid right?
There are no stupid questions,theres only stupid people.
Kidding.
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ask Straiga, I think he said he was an astronaut too.... maybe it was a cosmonaut.
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If I fart in space would I move forward?
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If you were next to me, I'd move somewhere.
But the fart molecules probably would not be as dense.
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Originally posted by Slash27
You watched 'Wing Commander':rofl
It was on cinemax last night believe it or not.
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Yes Sandman.
Think of it like a canoe.
You are standing in a canoe on a quiet, silent lake. You are at one end of the canoe.
If you calculate your mass and center of gravity and the mass and CoG of the Canoe, you would find that the CoG of both of you and the Canoe rests on a single point.
Now run to the other end of the canoe. The canoe will have pushed itself in the opposite direction that you were running.
Now get to the other end of the Canoe and stop. Calculate the CoG of you and the canoe, and you'd see that it would be in the exact same spot as it was before.
Now take your farting in space example. The methane gas you give off will have a mass and a center of gravity. Now, when you fart, you will be pushed in one direction while the gas in the other.
But the whole time the CoG of both you and the gas will remain in the exact same spot. Even if you drift millions and millions of miles away (assuming no outside interferance), the CoG will be in the same spot.
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You do not feel inertia in space. Only acceleration.
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Don't be silly. A body in motion will tend to stay in motion, intertia works exactly the same in freefall as it does on the earth. If you start spinning, the centripetal force on your inner ear muscles will cause vertigo.
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Go read up on centripital force.
http://www.answers.com/topic/centripetal-force
The only time you will feel anything is due to changes in velocity. Which by definition must involve an accleration.
g00b
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I've got a better idea, with respect, why do don't YOU post what you disagree with here instead of sending everyone off on a goose chase.
Inertia does not disapear when you enter freefall.
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Originally posted by g00b
Go read up on centripital force.
http://www.answers.com/topic/centripetal-force
The only time you will feel anything is due to changes in velocity. Which by definition must involve an accleration.
Inertia describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration.
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You should still go read it. But I'll copy the relevant bits.
centripetal force
The centripetal force is the force pulling an object toward the center of a circular path as the object goes around the circle. An object can travel in a circle only if there is a centripetal force on it.
In the case of an orbiting satellite the centripetal force is its weight and acts towards the satellite's primary; in the case of an object at the end of a rope, the centripetal force is the tension of the rope and acts towards whatever the rope is anchored to.
Centripetal force must not be confused with centrifugal force. In an inertial reference frame (not rotating or accelerating), the centripetal force accelerates a particle in such a way that it moves along a circular path. In a corotating reference frame, a particle in circular motion has zero velocity. In this case, the centripetal force appears to be exactly cancelled by a pseudo-force, the centrifugal force. Centripetal forces are true forces, appearing in inertial reference frames; centrifugal forces appear only in rotating frames.
Centripetal force must not be confused with central force either.
Objects moving in a straight line with constant speed also have constant velocity. However an object moving in an arc with constant speed has a changing direction of motion. As velocity is a vector of speed and direction, a changing direction implies a changing velocity. The rate of this change in velocity is the centripetal acceleration. Differentiating the velocity vector gives the direction of this acceleration towards the center of the circle.
By Newton's second law of motion, as there is an acceleration there has to be a force in the direction of the acceleration. This is the centripetal force.
You'll note the use of the term acceleration. There are some formulas on the linked page if you want to know the specifics. Basically if you are in or on a rotating spaceship you are experiencing a continuous acceleration (centripetal acceleration). If the rotation speeds up or slows down or changes direction you are experiencing an acceleration(angular acceleration). If the spaceship starts to actually move in one direction or another you are experiencing acceleration (linear acceleration).
Any change in velocity (The vector giving the speed and direction of motion of any object) requires an accleration.
I'm not a physics teacher so I hope that all makes sence.
g00b
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Originally posted by g00b
You'll note the use of the term acceleration. There are some formulas on the linked page if you want to know the specifics. Basically if you are in or on a rotating spaceship you are experiencing a continuous acceleration (centripetal acceleration). If the rotation speeds up or slows down or changes direction you are experiencing an acceleration(angular acceleration). If the spaceship starts to actually move in one direction or another you are experiencing acceleration (linear acceleration).
Any change in velocity (The vector giving the speed and direction of motion of any object) requires an accleration.
Inertia describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration.
Question for you. How does above explain your claim: "You do not feel inertia in space"?
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With respect, when you said:
Originally posted by g00b
You do not feel inertia in space. Only acceleration.
then
Originally posted by g00b
I'm not a physics teacher so I hope that all makes sence.
became very clear already.
I suspect you may be confusing terms. Inertia is present no matter where you are, in space or on the ground.
Additionally, you seem to have forgotten about Coriolis force. In the example you gave, people walking on the outside rim of the station would feel not only the downward "pull" against the floor, but also a slight precession as a result of the constant "acceleration" against the floor as the wheel turned in a circle.
For example, if you pee into a urinal on a rotating space station, you need to aim slightly to the side of where you want it to hit because of coriolis. Once it leaves your body, the urine will want to continue along the path it started, but since the rest of the environment is "accelerating" in an arc, it will seem to traverse an odd path indeed.
If you want to know why I know this, well, I could tell you, but I'd have to kill you. Ooops, gotta run, time to take another cargo load up to The Wheel from Nellis. :D
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Originally posted by lasersailor184
Yes Sandman.
Think of it like a canoe.
You are standing in a canoe on a quiet, silent lake. You are at one end of the canoe.
If you calculate your mass and center of gravity and the mass and CoG of the Canoe, you would find that the CoG of both of you and the Canoe rests on a single point.
Now run to the other end of the canoe. The canoe will have pushed itself in the opposite direction that you were running.
Now get to the other end of the Canoe and stop. Calculate the CoG of you and the canoe, and you'd see that it would be in the exact same spot as it was before.
Now take your farting in space example. The methane gas you give off will have a mass and a center of gravity. Now, when you fart, you will be pushed in one direction while the gas in the other.
But the whole time the CoG of both you and the gas will remain in the exact same spot. Even if you drift millions and millions of miles away (assuming no outside interferance), the CoG will be in the same spot.
LOL... it's something to think about while I'm farting. Thank you for that. :)
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"Question for you. How does above explain your claim: "You do not feel inertia in space"?"
I never claimed inertia is not present or non-existant.
Inertia is NOT a force. How can you feel something that is not a force?
I maintain....
You do not feel inertia in space. Only acceleration.
I'm done with this conversation.
g00b
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You can not feel Inertia, you can only see it.
If space was infinite and black, you would not know that you are moving, because you have nothing to judge this off of.
If you're going 60mph down the road, you can tell because the road marks are shooting past really really quickly.
But, thinking about this, I do believe Goob is technically correct. Inertia is momentum.
To change inertia (momentum) you need acceleration (either positive or negative). Therefor, you do not directly feel inertia, but the change in it.
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Originally posted by g00b
"Question for you. How does above explain your claim: "You do not feel inertia in space"?"
I never claimed inertia is not present or non-existant.
Inertia is NOT a force. How can you feel something that is not a force?
g00b
Acceleration is NOT a force either. How can you feel something that is not a force?
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Acceleration IS (basically) a force. The vital piece of information your missing though, is mass. Everything has mass, so everything that is accelerating is feeling a force.
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Originally posted by lasersailor184
Acceleration IS (basically) a force. The vital piece of information your missing though, is mass. Everything has mass, so everything that is accelerating is feeling a force.
Acceleration is "the rate of change of velocity of an object with respect to time". It is NOT a force.
To your previous post, and Goob's and why we talk about inertia.
Inertia does not equal momentum. In physics momentum is defined, inertia is not. Inertia (as we know it today) is just descriptive term which contains some of the ingredients necessary to feel G forces in space (that was the original question all about), mass, momentum and acceleration included.
So I will say it again (for the 3rd time): Inertia describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration.
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Force = Mass X Acceleration.
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its still beyound me why they dont build rotating space stations,
like "von Braun" suggested, to avoid the problems Humans get
while in space with zero Gravity, and we are now in 2005...
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OK, I can't help myself. 1 last time, as simple as possible.
In the big black void of space you can only percieve a CHANGE in velocity, correct? If you disagree here, I am at a loss for any further comment and give up entirely. Remember, velocity = speed AND direction.
To change velocity requires acceleration.
I maintain....
You do not feel inertia in space. Only acceleration.
g00b
GhostFT
It's a good idea, I think the problem is docking. Either you have to spin your dock or your incoming ship to match. Neither is easy and failure is catostophic. Solves alot of problems though.
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Everything takes energy. It would take a lot of energy to get a space station in orbit rotating at the correct velocity to generate earth like acceleration.
However, the problem is that it would take a lot more energy to keep the Station rotating at the correct velocity. Like my talks about Center of Gravity. Anytime a person moves, they throw off the center of gravity, and even the speed of rotation.
Anytime you put a weight in the station, be it even an apple, you change the center of gravity. The space station would have to adjust for this to keep in perfect rotation.
The real problem is not that we don't know how to do this.
The real problem is that we don't have an energy source capable of sustaining this. Rocket Fuel for example, takes up a lot of space, and mass. It burns a lot just getting the shuttle into space. Now, the space shuttle doesn't need a lot of rocket fuel to get back to earth because it is basically falling. You don't need energy to fall.
So until we figure out a super powerful clean compact power source, we're still going to be doing things the same way.
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Maybe you can help us poor dumb guys by defining exactly what inertia "feels" like on earth, then, so we can understand why you would not "feel" it in space.
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Originally posted by Chairboy
Maybe you can help us poor dumb guys by defining exactly what inertia "feels" like on earth, then, so we can understand why you would not "feel" it in space.
very simple.
run full speed into a wall. that point of time between the impact and the brain registering it is inertia.
:aok
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Originally posted by Chairboy
Maybe you can help us poor dumb guys by defining exactly what inertia "feels" like on earth, then, so we can understand why you would not "feel" it in space.
Maybe you should answer your own question.
How does one feel inertia?
And how can you percieve this WITHOUT acceleration?
Even Shanes glorious illustration of inertia, involves a sudden negative acceleration.
In a stagnant universe with NO acceleration (you could still have inertia) you would never feel anything because nothing would ever change. That's what inertia IS, the tendency to stay the same. I.e. No change.
g00b
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Inertia is best described as Momentum.
If you push an object in space it will continue to move on forever at that same exact velocity in that exact same direction (assuming no outside interference).
This is quantified as Mass X Velocity.
However, we on earth have outside interference.
Say you push a car in Neutral down the hill. Momentum (inertia) would tell us that it would go on forever, but this is not true.
The car would have friction on the axles slowing down the car. It will also have Wind Resistance pushing on the front of the car. Eventually, it will come to a stop somewhere down the road.
Like I said before, if you were in a car going 60, you would know. You can look out the window and see the trees moving past. You have some good guess as to how fast you are going, but your speedometer tells you exactly.
But when you are in the car, you feel nothing (disregard bumps in the road). If you were to close your eyes and sit still you would not know that you are actually moving. Movement can only be percieved.
Now, however, acceleration with respect to momentum is different. You can feel it when the driver steps on the pedal. Say you accelerate from a dead stop. You have 0 momentum because you have 0 velocity. When the car accelerates, you feel yourself pushed against the back of the seat.
When the car stops, you feel yourself pushed against the seatbelts.
Again, if you were to close your eyes and not hear the car (or the bumps in the road), you would feel yourself accelerate. You would feel yourself get pushed against the back of the car, and you would say to yourself, "Hmm, we are speeding up."
If you close your eyes and you feel yourself pushing against the seatbelt, you would say to yourself, "Hmm, we are slowing down."
So goob is correct.
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No, goob is not correct. What you are feeling on earth is not inertia, you're feeling the acceleration imposed by the various forms of drag around you (air, water, gravity, friction, etc).
Goob keeps using this word inertia... but I do not think it means what he thinks it means.
Lasersailor, when you're in a stopped car on Earth, you are not at 0 velocity. On one frame, you are moving at a little over 1,000 mph as the planet rotates. On another frame, you're moving around the sun at about 66,000 mph. The sun is orbiting the center of the galaxy at about 560,000 mph. The Milky Way is travelling at about a million miles per hour towards the Virgo supercluster, but at this point, it's awful tricky to figure out what these speeds are relative to, so, it's best to just not think about it.
To answer the original question of this thread, you would feel pushed down/red out stresses on pitchover in space if you were far from the center of mass, but if you were sitting in the middle, it would be a slight rocking sensation at best.
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Originally posted by lasersailor184
Force = Mass X Acceleration.
your previous claim was: Acceleration = Force which is incorrect.
Originally posted by lasersailor184
So goob is correct.
He claims inertia is nonexistent in space. This is incorrect. He claims (and so do you) that you feel acceleration.
I say you feel (have) inertia (in space) whenever there's change in motion.
Change in motion involves acceleration, but is only one part of it.
I'll say it again for the 4th time: Inertia (in space) describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration.
So, why would that be wrong and what makes your claim more precise or better?
It's like I'm pointing to a tree saying:"It's tree"
You're pointing out leaf and saying:"Not true, it's a branch, leaf is a proof I'm right."
Besides, with every post your "theory" changes.
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Originally posted by 2bighorn
He claims inertia is nonexistent in space. This is incorrect. He claims (and so do you) that you feel acceleration.
Nowhere do I claim inertia is nonexistant. As a matter of fact I clarify after your 1st falsity "I never claimed inertia is not present or non-existant." Your insisting I have claimed inertia is non-existant TWICE now, when I have never done so shows that you are either not reading my posts, or are simply making up your own facts as we go along.
My orignal apparently contentious statement was:
You do not feel inertia in space. Only acceleration.
I do not see ANY valid proofs presented by you or chairboy to the contrary.
Your statement "Inertia (in space) describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration." only strengthens my arguement as it is based upon the pre-requisite of acceration.
Inertia incorporates acceleration into it's very definition.
I really need to stop replying to this thread.
g00b
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Originally posted by g00b
I really need to stop replying to this thread.
Yes, but not for the reasons you think.
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Originally posted by g00b
You do not feel inertia in space. Only acceleration.
If you were sitting in the ISS on a couch reading this thread, instead of getting up & making yourself dinner, you would be feeling inertia.
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"You do not feel inertia in space. Only acceleration."
Tie yourself to the ISS put a relatively massive block of stuff in freefall beside you.
Push on it, feel that resistance to movement? That's inertia.
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Originally posted by Gh0stFT
its still beyound me why they dont build rotating space stations,
like "von Braun" suggested, to avoid the problems Humans get
while in space with zero Gravity, and we are now in 2005...
What most people ignore are some funny consequance of living in such a station. If you stay put then everything is fine and you feel earth-like gravity. Now, if you start walking and pick up some speed, you start feeling couriolis forces.
The interesting implication is that going one way around the station you'd feel stronger gravity and walking the other direction you'd feel lower gravity. If you walk fast enough in the direction opposite to the station rotation, you feel zero gravity...
If you have to carry a heavy 50 kg sack, just pick it up and start running in the right direction - it will get lighter and lighter till you can hold it on one finger. At that point you can lift both you feet off the floor and "fly" along the station.
This is because for an outside stationary viewer, you are hovering in one location while the station is rotating around you.
Stopping once you got to where you wanted might be a little tricky.
Bozon
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Bozon where did you get that Info from? first time i heard about this.
Very interesting, but i dont buy it right now ;)
But if its for real, i dont see a problem, just move in the right direction
and you would feel the G's like one earth, sitting is no problem at all
like you said. This could work, no?
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SPACE THE FINAL FRONTIER. THESE ARE THE VOYAGES OF THE STARSHIP ENTERPRISE, Dammit Sulu stop it, tha hurt Fk'r HER FIVE-YEAR MISSION TO EXPLORE STRANGE NEW WORLDS, Dammit Sulu...TO SEEK OUT NEW LIFE AND NEW CIVILIZATION, TO BOLDLY GO WHERE NO MAN HAS GONE BEFORE." Dammit Sulu that's it... Scotty Beam this Fk'r down!!!
Doc: Dammit Jim he's dead!
Jim: Dead? Scotty is Dead?
Doc: Yes, Dead Jim.
Jim: Sooooo who's beaming us down and back again?
Dammit Sulu knock it off, I swear you do that again I'll cut you...
Capt Kirk: Spock report....
Spock: In Captain...
Capt Kirk: And have you anything to..dammit Sulu stoppit!!! Spock meet me at the sick bay, Doc too... dammit let me go Sulu...
Now is when Nash rushes in and protects Sulu, swears that Jim killed Scotty and Spock is really CanaDUHian.
Frikken Liberals!
:D
Mac
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Actually, space is not a "zero gravity" environment... Gravity is the weakest of the 4 fundamental forces, but it is the farthest acting. Astronauts in orbit experience a zero gravity environment because their spacecraft is contiuously "falling" toward the earth. It's the same as becoming weightless on a rollercoaster when it goes downward. What prevents them from spiralling to their death is their forward velocity. Essentially, a spacecraft in orbit achieves an outward velocity equal to it's rate of descent. Because an object in motion tends to stay in motion, the astronauts inside are going forward while their spacecraft is falling away from them continuously.
If they are floating around and the spacecraft changes direction or velocity, they will feel "G" forces as soon as they come into contact with an inside surface of the spacecraft. If they are strapped into a seat at the time, they will feel "G" forces immediately.
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Exactly.
Watch out, though, gOOb might show up and try telling you how you're wrong because you'd be 'feeling inertia' or somesuch claptrap.
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Originally posted by bozon
What most people ignore are some funny consequance of living in such a station. If you stay put then everything is fine and you feel earth-like gravity. Now, if you start walking and pick up some speed, you start feeling couriolis forces.
The interesting implication is that going one way around the station you'd feel stronger gravity and walking the other direction you'd feel lower gravity. If you walk fast enough in the direction opposite to the station rotation, you feel zero gravity...
If you have to carry a heavy 50 kg sack, just pick it up and start running in the right direction - it will get lighter and lighter till you can hold it on one finger. At that point you can lift both you feet off the floor and "fly" along the station.
This is because for an outside stationary viewer, you are hovering in one location while the station is rotating around you.
Stopping once you got to where you wanted might be a little tricky.
Bozon
With feet you aint gonna do that.
Driving car inside the centrifuge would prove different results. You would still have to constantly overcome the air rushing against the car, so status quo, the weightlessness would be maintained only as long as you can insert opposite amount of energy. Also the energy equilibrium has to be kept in mind. More weight you would have initially, more energy would be required to reach the speed between floor and you equal to the spin.
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Maybe if schools would quit incorrectly teaching that gravity is an "invisible attractive force" instead of the bending of space, people would better understand it. After all, thanks to Einstein, we've known what it really is for about 100 years now.
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You guys might want to refer to this fourm for responses that are way above my paygrade.
http://orbit.m6.net/v2/forum.asp?forumid=6