Questions tagged [gravity]

Questions regarding the attractive force present between two masses. If about research in artificial gravity (i.e. manmade substitutes for gravity), please use the artificial-gravity tag.

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1answer
194 views

Time dilation between Earth and a similar planet revolving around a supermassive Black hole [closed]

I was thrilled watching 'Interstellar'. It was only much later that I came to realize certain anomalies in the movie (like the scene in which McConaughey approaches the Gorgantua — his body ...
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Is there really no difference between up and down in ISS?

ISS is actionally falling towards the earth and therefor they don't feel gravity. But ISS is falling in a direction towards the earth. So the astronauts living in ISS probably live in ISS in a manner ...
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What would it be like to walk on the Asteroid 216 Kleopatra?

Here is some renditions of 216 Kleopatra. Kleopatra is a relatively large asteroid, measuring 217 × 94 × 81 km.Calculations from its radar albedo and the orbits of its moons show it to be a ...
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Would my weight be constant on Pluto?

Since Pluto and Charon have distinct orbits around their barycenter (located approximately 960 km above Pluto's surface), the centripedal acceleration must be different on the outer hemisphere of ...
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Speed of Gravity [closed]

Is the speed of gravity instant? By the speed of gravity, I'm not talking about acceleration. What I mean is something like this: If I take a vacuum, for example, and put in two objects of the same ...
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How can an orbiting spacecraft's motions yield the orbitee's deep structure?

I've always been a fan of satellites like GRACE and GRAIL, where two satellites orbit a body, precisely measuring the changing distance between them in order to sense gravitational anomalies caused by ...
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1answer
447 views

Does Jupiter's high rotation speed affect its gravitational strength at the surface?

Jupiter's outer, equatorial atmosphere rotates at 12,517.12 meters/second, once every 9.5 hours, at a radius of 71,492 km. Geostationary orbital speeds for earth are around 3,000 meters/second, at a ...
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625 views

How are fuel requirements different for different types of orbits?

In theory, the orbit around a single mass always has the same amount of total energy (Kinetic + Potential). Therefore, if a satellite was launched from earth, it should always require the same amount ...
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How are the coefficients in the EGM96 model normalized?

For my own interest I'm trying to implement the EGM96 gravitational model. I found the coefficients here. The readme file says that they are "fully normalized", but I'm not 100% sure what this means. ...
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How can astronauts float in space without being affected by the gravitational force of nearby objects?

According to the Newton's law of universal gravitation: Any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely ...
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Why are the Trojan libration points equidistant and not mass weighted?

The locations of the collinear Lagrange points L1, L2, L3 are mass weighted, so for example Sun-Earth-L1 is only 1% of the distance to the Sun from Earth. But L4 and L5 are one AU from both the Sun ...
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Why is artificial gravity not included on space stations? [duplicate]

I'm wondering why artificial gravity is not included on the ISS, or on the currently planned OPSEK. There are long-term health effects of weightlessness, which would be avoided, using artificial ...
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Why did Voyager 2's velocity drop far below escape velocity before the first gravity assist?

As per @kasperd's comment on another question. Looking at the graph below, it appears that Voyager 2 started at just over escape velocity of the solar system. Just before the Jupiter flyby, it was ...
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Relationship between satellite's mass and orbital altitude

Is there a relation between the mass of a satellite and its orbital altitude? I mean, will a heavy satellite orbit at a higher or lower altitude than a lighter one, considering everything else being ...
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Could magnetic “boots” be used to simulate the effects of gravity for asteroid ships?

I have been to the Wikipedia pages on alternatives to gravity, and found the usual alternative forces, with the potential for magnets and the specious Russian claims, but I'm wondering why not just ...
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Pluto's satellites other than Charon orbits around Pluto or center of gravity between Pluto and Charon?

As the center of gravity between Pluto and Charon is outside Pluto does Pluto's satellites other than Charon such as Nix, Hydra, Kerberos or Styx orbits around Pluto or the COG?
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What ways can we get around the effects of microgravity? [closed]

One of the main factors limiting manned space exploration is the effects of living in zero-gravity on a long term basis. Aside from planting a big lump of rock beneath a starship or using a centrifuge ...
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Why are smaller celestial bodies like Ceres spherical?

When we look at larger objects (the Moon, Mars, Earth), they are pulled into spherical shapes by their own gravity. The question I have relates to smaller objects... those close to the threshold at ...
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Would human “superpowers” in low gravity fade away through reduced muscle mass?

If suddenly put in a low gravity as on the Moon or on Mars, humans should feel very strong, easily breaking some olympic records for example. Apollo astronauts have said that they did not get tired ...
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Do accelerometers rely on magnetism?

I'm reading some rules for a Mars-rover competition, and one of the rules says you are not allowed to use "Sensors that rely on the Earth’s magnetic field". So my question is - do accelerometers (...
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4answers
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Do the planets really orbit the Sun?

We often say that the planets orbit the Sun, which is usually a reasonable approximation. But in reality both Sun and the planets orbit the center-of-mass/center-of-gravity of the whole solar system, ...
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Why doesn't all space debris burn up? [duplicate]

Man-made satellites have to use boosters to accelerate to maintain orbit around the Earth. Space debris and old satellites with depleted boosters should be either pulled by Earth's gravity, or slowed ...
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What sensations would I feel on a Space Elevator?

For simplicity: Standard, 50,000km space elevator from equator to the counterweight. Acceleration, followed by constant velocity, followed by deceleration, and a stop past geostationary orbit. What ...
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How can gravity gradient forces be calculated?

I'm working on a theoretical problem that I came up with; Given the extremely low atmosphere in low Earth orbit (300-500 km), would an arrow that had orbital velocity keep flying 'true' due to the ...
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Use Pluto's gravitation to reach the next dwarf planet

Why doesn't New Horizons fly by nearer to Pluto so the gravitational pull would slingshot the probe to one of the next dwarf planets in the outer solar system (Eris, Haumea, Makemake,...)? I would ...
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Could we build a spaceship like the ones you see in Sci-Fi movies with current technology? [closed]

With our current technology could we build a spaceship like the ones you see in Sci-Fi movies (Enterprise in Star Trek or Star Destroyer in Star Wars)? Could self-gravitation be a problem? I would ...
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Is it possible for a human to walk on an asteroid?

"We’ll start by sending astronauts to an asteroid for the first time in history" (President Barack Obama on Space Exploration in the 21st Century".) With a very low gravity, an asteroid is not ...
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1answer
589 views

With what forces are Saturn's Rings cohesively held together? [closed]

With what sort of gravitation are Saturn's Rings held together? It is very spectacular and intriguing compared to the way Earth's gravitation acts. I do not have a basic or conceptual idea of what/...
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If there was a probe orbiting at the edge of Earth's Sphere of influence, how slow would it orbit?

Would it orbit very slowly? It's kinda been stuck in my head lately...
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760 views

How could the gravitational pull of a comet affect spacecraft and astronauts landing on it?

When I researched the gravity on comets like on 67P/Churyumov-Gerasimenko's surface I found that it was several hundred thousand times weaker than on Earth source: www.esa.int/Our_Activities/...
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501 views

Considering the relativity of time, how is time experienced in deep space? [closed]

To be more specific, if the relativity of time is governed by the mass and gravity of objects (I.E the satellites orbiting earth experience minor time dilation compared to us on the ground), how is it ...
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Is it possible to jump down a 10 meter building on Moon and be perfectly fine? [duplicate]

I was told that if you theoretically jump down from a three-floor building (assume 10 m) on the Moon surface, you will equally break your bones as in if you were doing that on Earth. I do not know why ...
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590 views

How can a body experience weightlessness or micro gravity on the ground? [closed]

I was thinking how to have a situation on Earth of feeling weightlessness for an indefinite time, not for a few minutes like on a diving plane Not reduced gravity, weightlessness as I feel in a ...
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Accelerometer in space

If my understanding of the General Theory of Relativity is correct, according to the Equivalence Principle, forces due to gravity and acceleration are indistinguishable. If that's the case, then an ...
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Is there a term for the distance from an object at which it's gravitational pull is negligible?

I used to think that there was a point at which you escaped the Earth's gravitational pull. This is technically false, since every object in the universe is attracted towards every other object. Is ...
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How fast could a person run on the Moon?

Measures of the vertical and horizontal vectors of athletes running shows that once they get up to speed the ratio of vertical to horizontal exertion is about 4:1. This paper by Jean-Benoit Morin Ph.D....
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Could weights make walking on the Moon feel like walking on Earth?

The Moon has about 1/6th of Earth's gravity, which (it is said) would perhaps lead to muscle degeneration for humans living there long-term. However, what if those humans wore bodysuits weighted to ...
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Is the velocity of orbiting around the earth exact?

Let's consider a satellite orbiting the earth. From the centripetal acceleration we have $v=\sqrt{g_{earth}r}$. If we know the $r$ and $g$, we can get $v$, which is the velocity needed to orbit around ...
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Gravity braking and orbit around same body in Low energy transfers

I recently read the discussion in the question, Gravity Assist Braking that momentum degradation used while entering in the opposite direction to the body's rotation in the Hill's Sphere of that body ...
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Multi level Gravity Wheel [closed]

If you had a space structure in the form of a disk shape. Inside it would have rooms and hall ways connecting the rooms. Each hall is a continues ring so if you walk in one direction in a hall you ...
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Why does lunar gravity decrease?

I was exploring some queries about the moon and came across the question Which artificial satellites in lunar orbit are currently active?. In this, the accepted answer says: The lunar gravity field ...
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Objects speeding up due to planets gravity?

I remember hearing that asteroids and other objects can actually gain speed while passing a planet or large object to due the gravity, but still not enter orbit. Is this true? If so, how is this ...
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Max g survivable suspended in water?

With something like a coil gun mass driver in mind where the more acceleration the cheaper the design in mind: If you were to suspend the astronauts in a shallow layer of water and horizontally ...
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Adapting to Increased Gravity on Alien Planets

What would mankind use in order to adapt or merely cope with the effects of a large increase of gravity on an alien world? Assuming there are no other problems we would face.
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On a Super-Earth 1.5x the volume and mass of Earth, would our rocket technology allow us to reach orbit? [duplicate]

To try and make parameters clear, can we say we are talking about 50% 'more Earth'? As in, Earth, but 1.5 times as big and heavy? And let us include the atmosphere. If there is 50% more of it by ...
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Standing at the top of a space elevator would 'up' be towards the Earth?

If I rode a space elevator to the top, assuming only natural forces apply, would the Earth be over my head or under my feet? If it was over my head how is that possible?
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How to simulate the environment of the moon for rovers on earth?

What technology or techniques are used to test rovers (that are designed to work on the moon, for example) on earth ? How can the environment (e.g. gravity) of the moon be simulated on earth?
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What would it look like to shatter a glass or break similar material in Zero Gravity?

I just had this thought today: I wonder what the shattering would look like if you "dropped" a glass or a ceramic cup in zero gravity. Obviously you can't drop it, you'd have to like throw it. But ...
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Why is momentum transferred to the moon?

The moon whizzes around the Earth, dragging water after it and producing tides. In a comment on this question, I asserted this would sap the momentum of the moon causing it to fall to Earth. This was ...
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How does gravitational stability change with the distance from special places such as geostationary orbit and lagrange points?

How rapid do the attractive properties of GEO and lagrange points deteriorate with the distance from optimum? How "large" are such locations? At what distance would station keeping require, say, twice ...