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BmanUltima t1_je9p6w2 wrote

G forces are based on change in velocity, but the unit is based on earth's gravity.

G forces are applied anywhere.

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ArcticHelix OP t1_je9pnf0 wrote

Is there a possible situation where they do not apply in turning?

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Upholder93 t1_je9sdyb wrote

Objects in freefall do not feel the effects of g-forces. This is why astronauts on the ISS are weightless, despite the gravity in LEO being almost the same as at the surface.

So it is possible for objects to move in a curve without feeling the effects of acceleration. However it requires they be accelerated by gravity and nothing gets in their way (the ISS is always accelerating toward the centre of the earth, it just has enough lateral momentum that it never hits it).

Conceptually, if you could create and manipulate gravitational fields, you could accelerate without feeling g-forces.

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b_a_t_m_4_n t1_je9tr5e wrote

Technically they're moving in a straight line through curved space. So they experience no inertial forces because their velocity never changes.

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Upholder93 t1_je9v3qg wrote

I was simplifying to a euclidean perspective, but yes, you're absolutely right.

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ArcticHelix OP t1_je9szaz wrote

Do you think that creating and manipulating gravity is possible in the future and if so would it be used?

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Upholder93 t1_je9ure2 wrote

The technology is the same as that necessary to manipulate space-time, so similar in notion to that used to create wormholes and warp bubbles, though perhaps a less complex application of it.

At present our theoretical understanding implies that this requires either exotic negative energy (which has not been proven to exist), or absolutely insane amounts of energy (think mass of planets level energies). So with our current understanding it's either physically or practically impossible.

However gravity is still probably the least we'll understood of the four fundamental forces, so it may be that future discoveries enable space-time manipulation for more reasonable energy expense. It's unlikely to happen soon, but if it can be done it will be. There is already research being done into reducing the energy demand, and much more into gravity itself.

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b_a_t_m_4_n t1_je9tv73 wrote

That would require that we understand what gravity is. And we don't yet.

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dirschau t1_je9pu5t wrote

"G forces" is only a common term for people being squished against stuff by inertia ("certrifigal force"). No gravity necessary.

The only connection to gravity is that it's measured in multiples of gravitation acceleration at the earth's surface, aka "g". Because it's something we're familiar with and it's easy to translate into effects on the human body.

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ArcticHelix OP t1_je9s5ix wrote

Will humans feel the same amount of gs in a turn in space and on earth or will one be able to turn sharper even if it is slight?

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dirschau t1_je9uirk wrote

The one difference in the same sharpness of turn between space and earth is that there's already 1g of acceleration always acting on you towards the earth.

So, say, a rocket liftoff always has 1g more acting on you than the pure acceleration of the rocket would suggest. Acceleration towards the ground would have you feel 1 less.

Any side-to-side will always point slightly towards the ground on earth (the earth's g and the side acceleration forming a triangle), while it would be a pure centrifugal effect in empty space. So technically on earth, you'd experience a slightly higher g force, but not by a full g (same as the hypothenuse of a traingle isn't the simple sum of the sides).

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triffid_hunter t1_je9pu6z wrote

> Since g forces are based on gravity

They're not, they follow f=mA.

A vessel with sufficient thrust could crush astronauts into a thin paste even if it's already in orbit.

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ArcticHelix OP t1_je9q1ms wrote

Do you think in the future this might affect space travel in any way?

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dirschau t1_je9vuub wrote

Not any more than it already does. We can't shoot people into space from a canon, the acceleration will kill them. Once you get past that idea, g forces aren't really the issue that needs solving. A rocket launch is about 3g's for the astronauts, something a healthy human (hence the rigorous health screenings) can withstand just fine, and that's pretty much the maximum they'll be subjected to (unless there's a crash).

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phoenixliv t1_je9pvu4 wrote

The sensation on zero g in space is because they’re in orbit falling around and around the planet. We’re affected by all the planets and the moon and everything in the universe to some small degree. Gravity is stronger when something is dense and or close though.

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ArcticHelix OP t1_je9satn wrote

Will space travellers in the future have to plan around the gravitational field of large objects in space? Or will it not be a problem

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phoenixliv t1_jed9o8l wrote

Yeah. They already do. Its physics, laws of nature and all that. It’s really interesting how scientists use gravity to slingshot things further into space

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Analyst7 t1_je9qvh7 wrote

You're conflating static G forces which are gravity based with acceleration forces. Your relative weight (static force) is higher or lower depending on the size of the mass exerting the force. Applied force (kinetic) is created by acceleration and are applied everywhere, even in space.

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space-ModTeam t1_je9te28 wrote

Hello u/ArcticHelix, your submission "G forces and turning in space" has been removed from r/space because:

  • Such questions should be asked in the "All space questions" thread stickied at the top of the sub.

Please read the rules in the sidebar and check r/space for duplicate submissions before posting. If you have any questions about this removal please message the r/space moderators. Thank you.

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b_a_t_m_4_n t1_je9tioy wrote

G-forces in the sense you mean are due to the inertia of mass. It's called G-forces because we use the earths gravity as a yardstick for measurement.

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