# Tag Info

0

The numbers you've quoted describe the pull of gravity Mars and Earth have on objects at their surfaces. This is based on both their mass and their volume. If you somehow squashed Mars down from its current size to half its radius (one eighth of its volume), that would increase its surface gravity by a factor of four, because its surface would be closer to ...

6

Firstly, orbital trajectories don't really depend on the mass of the orbiting object as long as the body they orbit (in this case the Sun) doesn't move. The force of gravity is: $$F = G\frac{m_1 m_2}{r²}$$ And the acceleration experienced by the orbiting object is: $$a = \frac{F}{m_2}$$ But combining them, we see that the acceleration is independent of the ...

6

There is a quite importand difference: Your vestibular apparatus (the natural accelerometer in your ears) works in the swimming pool exactly as usual. You are able to tell up and down. You will not get motion sickness. Other differences include: Your body is not perfectly homogenous in regard to density, so you will have some equilibrium posture and some ...

26

No. Water supports your body by applying pressure to your skin, with a bit higher pressure on the bottom due to being deeper. This supports the body as a whole quite nicely, but all of your insides are subject to the same forces as if you are lying on a very soft mattress under full gravity. Thus, for example, the heart still needs to exert the same effort ...

1

There isn't a qualitative difference between the two situations you've presented, only quantitative. (And neither one can meaningfully be called "artificial" - both situations are real microgravity, as explained in other answers. You might apply "artificial" to astronaut training neutral-buoyancy tanks (although it seems that the usual ...

1

Supplemental answer: Being the sticlker that I am I can not remain silent any longer. tl;dr: There are billions of billions of points in the universe with zero gravitational acceleration! While each answer includes some form of the "gravity is everywhere because it never ends" (i.e. $1/r^2$ never goes to zero so everything pulls on everything) I ...

1

Or more precisely isn't it similar to the zero-gravity created by those big zero-g airplanes Yes, it's identical Note that you use the phrase: artificial zero-gravity There is no such thing as "artificial zero-gravity". It's a meaningless phrase. Note that you use the phrase: zero-gravity There is no such things as zero-gravity. Pilots etc. ...

5

It is exactly the same zero gravity as you experience in a plane paraboling to Earth. It 's a bit different from the gravity you experience in far-from-mass gravity in outer space though. In the ISS gravity is nearly zero at every point. But not precisley (though it is not easy toy measure if not impossible). There is always a gradient giving rise to tidal ...

76

Gravity is everywhere. There is never any actual true "zero gravity" in the universe. But if you're in freefall - meaning following gravity's pull rather than resisting it, or being blocked from following it (by the floor, your nearby planet, spaceship walls as it thrusts, or whatever) - you don't feel it, and that's the thing we call "...

8

The right way to think about it is that, always and everywhere, weightlessness is the "artificial" kind. It is certainly true that the gravitational field is very weak far from any masses, but on the way to the moon the astronauts were coasting in free fall so it made no difference to their experience what the gravitational field strength was. Even ...

26

Gravity has infinite range, so there is nowhere in the universe where you can be free from its influence. Sure, there are places such as supervoids where the influence of gravity will be very little, but there's nowhere where it is absent entirely. The day to day experience of 'gravity' - the feeling of standing on the surface of a planet - isn't really the ...

53

This is a point worth emphasizing: When you dive off a high dive, or go on a free fall ride at an amusement park, or fly on Virgin Galactic, you are experiencing weightlessness in exactly the same way as the astronauts on the ISS. At the height of the ISS, the earth's gravity is about 90% of what it is at sea level. You could launch a rocket straight up and ...

-2

Virgin Galactic's flights are sub-orbital and pass below the Kármán line (about 100 km up), so technically the passengers don't qualify as astronauts in space, but while they experience weightlessness, this is a consequence of the trajectory of their spacecraft rather than them being unaffected by Earths gravity. The force of gravity on the occupants of ...

33

Yes, for a few minutes. It is similar to what is done in a zero gravity airplane flight, but a longer period of time. Also, orbital weightlessness is basically the same thing, the spacecraft and you are falling at the same rate.

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