Zero G . Illusion or reality?
Discussion
Watching a film about this the other day, and suddenly the light bulb lit up!.There is no zero gravity as such, as in outer space. The plane is still within the pull of the earths gravitational field so surely the plane is falling just a bit faster than the bodies inside? So what they are actually doing is freefalling in an enclosed environment.
Am i correct, or was it the whisky having a random thought?
Am i correct, or was it the whisky having a random thought?
silverfoxcc said:
Watching a film about this the other day, and suddenly the light bulb lit up!.There is no zero gravity as such, as in outer space. The plane is still within the pull of the earths gravitational field so surely the plane is falling just a bit faster than the bodies inside? So what they are actually doing is freefalling in an enclosed environment.
Am i correct, or was it the whisky having a random thought?
Indeed. What we refer to as "zero G" in orbit is really just plummeting towards the earth but continuously missing it. It's no more zero gravity than being trapped in a falling lift, except without the messy bit at the bottom of the shaft.Am i correct, or was it the whisky having a random thought?
Gravity is always there I thought.
Some inane ramblings.
Depends what you are close to and falling around, that is what has the influence over you or you influence it. So in orbit you are falling but not hitting anything, your speed is such that you continue not to hit anything.
On the way to the moon there is a point where the Earth loses influence and the Moon takes over, think one books says the astronauts were doing a mere 5000mph at that point. But to get to the moon it was still an orbit where they were falling around something and not hitting it.
Deep space?
Some inane ramblings.
Depends what you are close to and falling around, that is what has the influence over you or you influence it. So in orbit you are falling but not hitting anything, your speed is such that you continue not to hit anything.
On the way to the moon there is a point where the Earth loses influence and the Moon takes over, think one books says the astronauts were doing a mere 5000mph at that point. But to get to the moon it was still an orbit where they were falling around something and not hitting it.
Deep space?
jmorgan said:
Gravity is always there I thought.
Some inane ramblings.
Depends what you are close to and falling around, that is what has the influence over you or you influence it. So in orbit you are falling but not hitting anything, your speed is such that you continue not to hit anything.
On the way to the moon there is a point where the Earth loses influence and the Moon takes over, think one books says the astronauts were doing a mere 5000mph at that point. But to get to the moon it was still an orbit where they were falling around something and not hitting it.
Deep space?
If you're not in orbit though, just at the point where the gravitational fields sum to zero (there must be a name for it, but A-level Physics was decades ago). That's zero gravity isn't it?Some inane ramblings.
Depends what you are close to and falling around, that is what has the influence over you or you influence it. So in orbit you are falling but not hitting anything, your speed is such that you continue not to hit anything.
On the way to the moon there is a point where the Earth loses influence and the Moon takes over, think one books says the astronauts were doing a mere 5000mph at that point. But to get to the moon it was still an orbit where they were falling around something and not hitting it.
Deep space?
dr_gn said:
If you're not in orbit though, just at the point where the gravitational fields sum to zero (there must be a name for it, but A-level Physics was decades ago). That's zero gravity isn't it?
The Lagrange points? No, that's just where the gravity sums to zero. Imagine a tug of war with evenly matched teams. Plenty of forces, but nobody is moving. If there was enough gravity you'd get torn in two, even at a Lagrange point.davepoth said:
dr_gn said:
If you're not in orbit though, just at the point where the gravitational fields sum to zero (there must be a name for it, but A-level Physics was decades ago). That's zero gravity isn't it?
The Lagrange points? No, that's just where the gravity sums to zero. Imagine a tug of war with evenly matched teams. Plenty of forces, but nobody is moving. If there was enough gravity you'd get torn in two, even at a Lagrange point.If I remember my first-year Physics lectures correctly, there is actually no experiment that can be done to distinguish an accelerating frame of reference from a gravitational field (consequence of general relativity). So while there is a gravitational field acting inside an orbiting spacecraft, counteracted by the acceleration of its freefall, that's totally indistinguishable from the gravitational fields due to 2 masses counteracting each other (a Lagrange point).
As far as being torn apart at a Lagrange point, what you have to remember is that a Lagrange point is just that, a point, infinitely small. There is actually no gravitational force on the infinitesimal part of you (or your spaceship) that's at the Lagrange point, but most of you isn't, it's just close to it and so might have a lot of gravity acting on it.
In fact, whenever you hear about something being "torn apart by gravity", what's actually happening is that the gravitational forces on different parts of it are different.
As far as being torn apart at a Lagrange point, what you have to remember is that a Lagrange point is just that, a point, infinitely small. There is actually no gravitational force on the infinitesimal part of you (or your spaceship) that's at the Lagrange point, but most of you isn't, it's just close to it and so might have a lot of gravity acting on it.
In fact, whenever you hear about something being "torn apart by gravity", what's actually happening is that the gravitational forces on different parts of it are different.
dr_gn said:
Eric Mc said:
Even objects that have found themselves at a point in space where the gravitational pull of two bodies cancel out are still in free fall.
What are they falling towards in this scenario?If the spacecraft was travelling sufficiently fast enough to escape the solar system, it would no longer be "falling" around the sun but would be in its own orbit around the central gallactic core. So, if it found itself at the neutral point between (say) two stars, it would still be "falling" around the gallactic core - as all the stars of the Mily Way galaxy are.
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