Artificial Gravity in Films
Discussion
Ok, so in 90% of films space stations/craft have a section that rotates iot create artificial g.
I was watching mission to mars (not a great film) yesterday and one character is walking on the inside of the rotating bit using (i'm guessing) centrapedal force to replace gravity. That seemed to make sense to me until another character enters the rotating section through a tunnel going through the centre of rotation where he was weightless.
My thought is if you're weightless in the middle and move to the edge you'd stay weightless as everything would just move round you? Does that mean a spinning section won't replace gravity?
I was watching mission to mars (not a great film) yesterday and one character is walking on the inside of the rotating bit using (i'm guessing) centrapedal force to replace gravity. That seemed to make sense to me until another character enters the rotating section through a tunnel going through the centre of rotation where he was weightless.
My thought is if you're weightless in the middle and move to the edge you'd stay weightless as everything would just move round you? Does that mean a spinning section won't replace gravity?
Benengo said:
Ok, so in 90% of films space stations/craft have a section that rotates iot create artificial g.
I was watching mission to mars (not a great film) yesterday and one character is walking on the inside of the rotating bit using (i'm guessing) centrapedal force to replace gravity. That seemed to make sense to me until another character enters the rotating section through a tunnel going through the centre of rotation where he was weightless.
My thought is if you're weightless in the middle and move to the edge you'd stay weightless as everything would just move round you? Does that mean a spinning section won't replace gravity?
Someone has too much time on their hands.I was watching mission to mars (not a great film) yesterday and one character is walking on the inside of the rotating bit using (i'm guessing) centrapedal force to replace gravity. That seemed to make sense to me until another character enters the rotating section through a tunnel going through the centre of rotation where he was weightless.
My thought is if you're weightless in the middle and move to the edge you'd stay weightless as everything would just move round you? Does that mean a spinning section won't replace gravity?
Ozone said:
A great film 
- also why when they are all outside the spaceship and one of the crew flies off without a tether, does the woman not have enough power to rescue him? Surely you don't need the thrusters continually on to keep moving in space as it is a vacuum?
Woman driver. Needs constant small adjustments!!!! - also why when they are all outside the spaceship and one of the crew flies off without a tether, does the woman not have enough power to rescue him? Surely you don't need the thrusters continually on to keep moving in space as it is a vacuum?Unless you are stood on the spinning bit, then you would be weightless. The only reason the spinning bit 'replaces' gravi is because when you are spinning, the onward momentum of an object simply means it 'app eras' to fall to ground, when in actual fact the spinning ground is coming up to meet the object.
You can indeed rotate around a point and centripetal reaction force could be used to emulate gravity as I understand it. However the "gravity" would start at nothing at the centre of rotation and increase toward the maximum radius. Your head would be pulled at less than your feet.
My guess is that humans exposed to a relatively small radius artificial gravity environment would puke their guts up with appalling regularity.
Another option would be to design a craft that you attach via a very, very strong cable to a massive but compact boulder (or similar) that you then rotate around. In the craft "gravity" would then all work in one direction.
This is a problem. Given the length of even short interplanetary journeys it would be vital for human health to expose the occupants of a craft to "gravity" sufficiently to avoid muscle loss else they'd be jelly and useless by the time they got to the destination! And AG isn't an easy problem to solve.
My guess is that humans exposed to a relatively small radius artificial gravity environment would puke their guts up with appalling regularity.
Another option would be to design a craft that you attach via a very, very strong cable to a massive but compact boulder (or similar) that you then rotate around. In the craft "gravity" would then all work in one direction.
This is a problem. Given the length of even short interplanetary journeys it would be vital for human health to expose the occupants of a craft to "gravity" sufficiently to avoid muscle loss else they'd be jelly and useless by the time they got to the destination! And AG isn't an easy problem to solve.
It's the rotational motion that substitutes for gravity. This creates the centripetal force that is the substitute. If you think of it in terms of centrifugal force it will be confusing. If you aren't spinning with the spinning, um, bit, you'll experience no gravity. This means, if you were on the floor, and ran in a direction opposite to the spin but with equal speed, you'd be weightless and if you jumped up you'd float.
In fact, the act of running would be enough to make this so. On the other hand, if you ran in the same direction as the rotation you'd increase the force acting on you and you'd feel heavier. Also, the person floating from the centre access could float all the way towards the floor, and sort of walk on their hands along the floor without experiencing any gravity. They could then push against the floor rotating above their head and float all the way back to the entrance. As soon as they hold on to any part of the spinning section however, and gain some rotational motion, they will start to experience the artificial gravity.
In fact, the act of running would be enough to make this so. On the other hand, if you ran in the same direction as the rotation you'd increase the force acting on you and you'd feel heavier. Also, the person floating from the centre access could float all the way towards the floor, and sort of walk on their hands along the floor without experiencing any gravity. They could then push against the floor rotating above their head and float all the way back to the entrance. As soon as they hold on to any part of the spinning section however, and gain some rotational motion, they will start to experience the artificial gravity.
being as we don't know how gravity works in the first place, artificially creating it isn't going to be straightforward.
As said you could spin the thing, but it would have different forces at your feet and head. Like those rides at the funfair.
Although a wall of death works, doesn't it?
As said you could spin the thing, but it would have different forces at your feet and head. Like those rides at the funfair.
Although a wall of death works, doesn't it?
Edited by davethebunny on Tuesday 5th October 15:28
davethebunny said:
being as we don't know how gravity works in the first place, artificially creating it isn't going to be straightforward.
As said you could spin the thing, but it would have different forces at your feet and head. Like those rides at the funfair.
Although a wall of death works, doesn't it?
We don't know how gravity works but IIRC from a level physics it's an attractive force between masses that can be demonstrated in the lab.As said you could spin the thing, but it would have different forces at your feet and head. Like those rides at the funfair.
Although a wall of death works, doesn't it?
The thing about the centripetal forces involved in cinematic artficial gravity scenarios is that they require gravity to work... Without gravity there isn't anything to keep you stuck to the cylinder if you let go.
About 53 seconds in. Watch the astronaut running around the lockers.
http://www.youtube.com/watch?v=oYsKGDJe4zE
http://www.youtube.com/watch?v=oYsKGDJe4zE
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