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lwymarie
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since the moon also has gravity, does it attract earth?
Absolutely! The moon and Earth exert the same force on each other.lwymarie said:since the moon also has gravity, does it attract earth?
Doc Al said:Absolutely! The moon and Earth exert the same force on each other.
The moon's tidal effect on the Earth is due to the variation of the moon's gravitational pull on the earth, which exerts a stretching force along the earth-moon line. Thus there are two tidal bulges: one on the side of the Earth nearest the moon, one on the other side of the earth. And thus, due to the Earth's rotation, approximately two high tides per day. (Whether the moon is "out" or not.)hexhunter said:thats why we have high tides when the moon is out,
First off, tidal forces affect everything: solid Earth as well as the oceans. Of course the oceans, being fluid, deform more easily. The tidal force on your body due to the moon would be ludicrously tiny.and as we're 70% (roughly) water ourselves, it must also effect us...
The gravitational field of the Earth is certainly greater than the moon's, but the gravitational force they exert on each other is the same! (This must be true from Newton's 3rd law.) Consider that the moon's smaller gravitational field acts on the much larger Earth will exert the same force as the Earth's larger field does on the smaller moon. The gravitational force between the Earth and moon is given by this formula:lwymarie said:the same force? but Earth's gravity is greater!
Because they are moving sideways! If you could somehow stop the sideways motion of a planet, that planet would then fall into the sun.and why do planets orbit the sun but not bump into it?
lwymarie said:the same force? but Earth's gravity is greater!
It is believed that on full moons, the moon has an effect on the water in our bodies, causing more homicides and scuicides. This is where lunatic comes from luna=moonhexhunter said:thats why we have high tides when the moon is out, and as we're 70% (roughly) water ourselves, it must also effect us...
Doc Al said:...The tidal force on your body due to the moon would be ludicrously tiny.
Doc Al said:Because they are moving sideways! If you could somehow stop the sideways motion of a planet, that planet would then fall into the sun.
hexhunter said:thats why we have high tides when the moon is out, and as we're 70% (roughly) water ourselves, it must also effect us...
lwymarie said:Sorry I don't understand what 'sideway' means. Would you like to further explain please?
SpaceTiger said:[tex]\begin{picture}(150,150)(0,0)
\put(30.,19){\circle*{200}}
\put(130.,19){\circle*{5}}
\put(130.,19){\vector(0,1){30}}
\put(130.,19){\vector(-1,0){30}}
\put(140.,39){v}
\put(90.,0){F}
\end{picture}[/tex]
Basically, the planet is moving in the direction of the "v" vector and the star is pulling it in the direction of the "F" vector. Newton's first law says that an object in motion wants to continue motion in the same direction, so the planet wants to move forward. The force from the sun, however, is pulling it inward. In the next moment, it will have moved forward a bit, but it will also have moved in towards the star a bit, so its net motion will be forward and slightly to the left. It will continue to this behavior as time goes on and the total effect will be motion in an ellipse. The Earth's orbit is circular and that's a special case of an ellipse.
lwymarie said:so why some orbits are ellipses and some are circles? what is the principle behind?
lwymarie said:so why some orbits are ellipses and some are circles? what is the principle behind?
tony873004 said:Circular orbits don't really exist except on paper.
lwymarie said:so why some orbits are ellipses and some are circles? what is the principle behind?
lwymarie said:since the moon also has gravity, does it attract earth?
yomamma said:It is believed that on full moons, the moon has an effect on the water in our bodies, causing more homicides and scuicides. This is where lunatic comes from luna=moon
lwymarie said:so why some orbits are ellipses and some are circles? what is the principle behind?
Doc Al said:The gravitational field of the Earth is certainly greater than the moon's, but the gravitational force they exert on each other is the same! (This must be true from Newton's 3rd law.) Consider that the moon's smaller gravitational field acts on the much larger Earth will exert the same force as the Earth's larger field does on the smaller moon. The gravitational force between the Earth and moon is given by this formula:
[tex]F = G \frac{M_{earth} M_{moon}}{R^2}[/tex]
Note that it doesn't matter which is which--two objects always pull on each other with the same force. (Of course, since the moon is much smaller than the earth, that same force will have a much greater effect on the moon than on the earth. The Earth barely budges, but the moon circles the earth!)
Because they are moving sideways! If you could somehow stop the sideways motion of a planet, that planet would then fall into the sun.
'Lunatic' better describes the witchcraft-fearing fools that believe such susperstitious nonsense. Tidal/gravitational forces act the same on the 70% of us that's water as they do on the 30% of us that's made of non-water.yomamma said:It is believed that on full moons, the moon has an effect on the water in our bodies, causing more homicides and scuicides. This is where lunatic comes from luna=moon
x8jason8x said:in velikovsky's worlds in collision, he describes the collisions of venus, Mars and Earth within the last 8 to 15,000 years. Isn't it possible that such a collision could happen with the sun, assuming of course that any of the body in question withstood the temperatures?
Yes, everything does attract everything else in a space shuttle, this is why the term "microgravity" is used to describe this situation. The reason things held to the floor are twofold; The items are in the shuttle so its mass surrounds them and pulls in all directions and the gravity is very, very small. The orbiter has a mass of 75,000 kg. if you were standing on its hull, the closest you could get to its center would be about 3 meters. Acceleration due to gravity is equal toLinkk06 said:I know this is a bit off topic with the Earth and moon, but it has to do with everything with mass having gravity. Up in space astronauts float because they're far enough away from any planets or the moon that no gravity is keeping them to the floor, right? Well the astronauts, and the shuttle they're in, and everything near them has gravity, right? So why don't the things with large masses, like the space shuttle, attract other things like the astronauts and keep them to the floor? They both have gravitational pull so you wouldn't think they'd just float around. Or why doesn't the gravitational pull of the astronauts attract a piece of paper or another astronaut, since they don't have Earth's gravity to make a greater influence?
Another question, if the Earth's gravitational pull in space is enough to keep the moon or a space shuttle in orbit, why isn't it enough to pull the astronauts towards it and keep them to the floor (or ceiling or whatever's closest) instead of letting them float around?
Personally, I think it's more a skewed perception thing. How many times have you seen a crime committed and thought it was significant that it happened under a waning gibbous Moon?ohwilleke said:The effect exists, the cause does not. The believed cause is that more light makes it easier to carry out outdoor activities.
Starship said:So does that mean that motion is acausal? Do bodies stay in motion for no reason at all? If a particle at rest is caused to move in a certain direction, what keeps it moving in the same direction after the initial force is taken away?
ohwilleke said:The effect exists, the cause does not. The believed cause is that more light makes it easier to carry out outdoor activities.
x8jason8x said:in velikovsky's worlds in collision,...
Phobos said:Velikovsky was a bit of a crackpot. So, let's not muddle this particular topic with his ideas. But you can discuss Velikovsky's ideas in a new topic if you want. Thanks.