Question on gravity

[n_ka15]

If gravity is based on a higher mass = higher pull, then why does the earth pulls us so we dont lavitate, and the moon is a different experience... It has to be more than that...

PS: I try to figure out how gravity works in order to progress with my theory about lavitation...

[insane_alien]

the moon does get pulled and quite strongly too. it is moving though. and moving things tend to go in a straight line so gravity pulls it in a circle.

[n_ka15]

the moon does get pulled and quite strongly too. it is moving though. and moving things tend to go in a straight line so gravity pulls it in a circle.

 

Yes that I know but my question is, not the moon bieng pulled, but the moon pulling us, as it is much of a higher mass then we are, therefore it still should pull us with about the same amought of gravity as the earth... Maybe the atmosphere is blocking and concentrating the gravity within its borders somehow...

[insane_alien]

it does pull on the earth just as much.the earth and moon actually orbit round a barycenter that is just off centre with the earth. its only slightly off because the earth is so much more massive than the moon.

[Cap'n Refsmmat]

The Moon is of a much lower mass than the Earth, so the Earth pulls harder than the Moon. The Moon is also 250,000 miles away, whereas the Earth is just under our feet.

[n_ka15]

The Moon is of a much lower mass than the Earth, so the Earth pulls harder than the Moon. The Moon is also 250,000 miles away, whereas the Earth is just under our feet.

 

Yes but still, when you compare the moon to our mass, the gravity should still be as hard, also when astronouts land, there is no gravity, or is there?

[Cap'n Refsmmat]

Our mass doesn't matter in gravity (at least, not a great deal). We are dealing with the masses of the Earth and the Moon here. The Earth has a large mass, the Moon a mass 1/6th as big; the Moon is many thousands of miles away, the Earth is right here. Each makes the Earth's gravity much stronger than the Moon's where we are.

 

For astronauts who have landed on the Moon, the gravity there is 1/6th as strong, meaning that a person who weighs 180 pounds on Earth would way 30 pounds on the Moon.

[Sisyphus]

(Not that it matters much, but the moon is about 1/80 the Earth's mass, not 1/6. The surface gravity is 1/6, but that's because the moon's radius is much smaller than the Earth's, and you're closer to the center when standing on the surface.)

[Cap'n Refsmmat]

Ah, right, thanks. I thought that sounded suspicious when I said it.

[swansont]

Yes but still, when you compare the moon to our mass, the gravity should still be as hard, also when astronouts land, there is no gravity, or is there?

 

What do you mean by "our" mass? The earth, or a person?

 

F = GMm/r²

 

You can go ahead and calculate relative sizes of the force

[ydoaPs]

Yes but still, when you compare the moon to our mass, the gravity should still be as hard, also when astronouts land, there is no gravity, or is there?

 

The moon is a lot less massive than the Earth and it is far further away from us. Like swansont said, [math]F=G{\frac{{m_1}{m_2}}{r^2}}[/math] Where m₁ and m₂ are the masses of the objects in question(you and either the moon or the earth) and r is the distance between you and the centre of the other object. With the Earth being so much closer and more massive, it wins by a long shot until we get much closer to the moon. Even when we are on the moon, it holds us a lot less than the Earth does when we are on the earth.

[n_ka15]

The moon is a lot less massive than the Earth and it is far further away from us. Like swansont said, [math]F=G{\frac{{m_1}{m_2}}{r^2}}[/math] Where m₁ and m₂ are the masses of the objects in question(you and either the moon or the earth) and r is the distance between you and the centre of the other object. With the Earth being so much closer and more massive, it wins by a long shot until we get much closer to the moon. Even when we are on the moon, it holds us a lot less than the Earth does when we are on the earth.

 

K thanks, so what is gravity is it a magnetic field, how is it different than the normal magnet we have on earth, why is there no gravity in space, and what holds the planets if there is no gravity...

ps: sorry for the stupid questions, im just thinking in a rush, which causes in the lack of logic...

[insane_alien]

gravity is not a magnetic field, it is a seperate effect.

there is gravity in space and gravity holds planets because there is gravity.

[n_ka15]

K has there been any reaserch on gravity for a compleete 100% understanding of what it is and how to harness it...

[Sisyphus]

Gravity is a force which attracts every piece of matter to every other piece of matter, from a pebble to a human being to planets and stars. It is everywhere. It cannot be blocked, and it cannot be lessened except by moving farther apart. The larger the piece of matter, the more it pulls on other matter, and the more other matter pulls on it. It is what holds planets, stars, and galaxies together. It is what causes the Moon to orbit around the Earth and the Earth to orbit around the Sun, instead of just flying apart in straight lines.

 

K has there been any reaserch on gravity for a compleete 100% understanding of what it is and how to harness it...

 

As I said above, it is a force that exists between all objects. It can also be understood as a field (somewhat like magnetism), or even as the "shape of space." All of these are just mathematical models for predicting behavior, and we know pretty much exactly how it behaves in any given situation. Beyond that, "what it is" is kind of mysterious.

 

As for "harnessing it," we've been doing that since the stone age! Any machine that needs there to be an "up" and "down" in order to work "harnesses gravity." Look at a water wheel. Gravity makes water flow downhill, and we harness the energy of that gravity by using the water's flow to turn a wheel.

[sammyooba]

If you mean harness as in making gravity and the such, there's a group of Australian scientists trying to do this:

 

http://www.electrogravityphysics.com/html/artificial_gravity.html