soorejmg
http://www.astronomy.ohio-state.edu/~pogge...t4/gravity.html

I saw a lecture about how moon moves around the earth..Its expanation is as given below>I took it from link above.

The Orbit of the Moon
Falling apples are one thing, but what about the Moon?
What keeps the Moon in orbit around the Earth?
The Law of Inertia (Newton's 1st law) predicts:

If there were no gravitational force acting between the Moon and the Earth, the Moon would travel in a straight line at a constant speed.

But, of course the Moon really moves along a curved path:

It is deflected from a straight-line path by the force of gravity.
This causes the Moon to fall a little bit towards the Earth at the same time at it moves to one side.

WHAT I WAN TO KNOW IS HOW IS THE MOON GETTING ENERGY TO MOVE ???hOW COULD IT MOVE IN A STRAIGHT LINE??!!!BY SELF??THERE SHOULD BE SOMETHING TO PUSH THE MOON RIGHT?? THEY SAY ITS MOVING IN A CURVE SHAPE AS AS RESULT OF A FORCE OF LINEAR MOTION OF MOON AND EARTH.aLLTHESE AGE FROM WHERE DID MOON GET THIS ENEGY TO MOVE IN LINEAR PATH..
soorejmg
some one can help me/??i am really intersetd
Lsos
QUOTE (soorejmg+Sep 28 2006, 05:25 PM)

WHAT I WAN TO KNOW IS HOW IS THE MOON GETTING ENERGY TO MOVE ???hOW COULD IT MOVE IN A STRAIGHT LINE??!!!BY SELF??THERE SHOULD BE SOMETHING TO PUSH THE MOON RIGHT?? THEY SAY ITS MOVING IN A CURVE SHAPE AS AS RESULT OF A FORCE OF LINEAR MOTION OF MOON AND EARTH.aLLTHESE AGE FROM WHERE DID MOON GET THIS ENEGY TO MOVE IN LINEAR PATH..

It started moving billions of years ago and there's nothing to stop it from doing so. Once something starts moving, and there's nothing to slow it down, it's just going to keep moving. That's the most fundamental law of physics. I learned this when I was 5 years old....
Ron
Hi Soorejmg,
Newton's first law states simply 'anything in motion stays in motion and anything at rest stays at rest unless acted upon by an outside force'. The straight line analogy assumes the moon is already moving. ( could be from some cosmic event that created the solar system ...), but why it revolves around the Earth is Gravity (an outside force). How it revolves around the earth is something like: If you drop an apple from 10feet high it will fall and hit the earth(gravity again). If you dropped that apple from alot higher than 10 ft, you might hit the earth or you might miss the earth (I'm talking very far away). If you missed the earth the apple would fly past the earth, but then gravity would start to pull it back towards the earth at some point. If it missed again the same thing would happen over and over again. This is now an apple in orbit!
I hope this helps a little.
Ron
soorejmg
QUOTE (Ron+Sep 28 2006, 06:26 PM)
Hi Soorejmg,
Newton's first law states simply 'anything in motion stays in motion and anything at rest stays at rest unless acted upon by an outside force'. The straight line analogy assumes the moon is already moving. ( could be from some cosmic event that created the solar system ...), but why it revolves around the Earth is Gravity (an outside force). How it revolves around the earth is something like: If you drop an apple from 10feet high it will fall and hit the earth(gravity again). If you dropped that apple from alot higher than 10 ft, you might hit the earth or you might miss the earth (I'm talking very far away). If you missed the earth the apple would fly past the earth, but then gravity would start to pull it back towards the earth at some point. If it missed again the same thing would happen over and over again. This is now an apple in orbit!
I hope this helps a little.
Ron

Heyy It helps not little..MY DOUBTS ARE 80% over.It was a very clear explanation...

I imagined it like this.I am standing ,Now one of my friend trying to pass in a straight line in front of me.I catch him and he trying to move and resluting in a orbital motion..

But what if his or my strenght was greater.Isnt it surrisin gthat these forces are balanced!!!!If mine was greater then he would come towards me and if his was greater then he would leave.Same in case of moon and earth..
How is it staying so??!!!How come earths power and moons power was balanced???!!!!!!!!!!!!!1
Zephir
QUOTE (soorejmg+Sep 28 2006, 08:25 PM)
what i wan to know is how is the moon getting energy to move ???how could it move in a straight line??!!!by self??there should be something to push the moon right?? they say its moving in a curve shape as as result of a force of linear motion of moon and earth.all these age from where did moon get this energy to move in linear path..

The simplest answer can sound, the particles are moving through vacuum like wave packets. Because the vacuum is more dense near the massive objects, it curves the path of such waves like lens to the circular path.

The Aether Wave theory (AWT) supplies even more detailed explanation of gravitational field. By such way the matter really wants to move along most straight line as possible. But the vacuum environment is formed by the bubbles of dense foam (i.e. Aether). Such foam is more dense around massive objects and the attractive force is the result of the tendency of less dense bubble to level the concentration. The more curved bubbles inside particles of Moon are trying to found the more dense places, because in such places they don't feel "so much curved" with respect of it's environment. You can check such behavior by using a tiny bubbles carefully blowed beneath surface of soap solution.

So we can say, the curved path of matter motion is the result of the tendency to found the less curved path as possible. Problem is, the path of particle inside of matter is strongly curved, so they're always trying to found the compromise: the more dense vacuum, where the internal curvature inside particles isn't so pronounced. Such vacuum is surrounding each the massive object, too - so that the massive particles are attracted by the massive matter.
Guest_Confused2
Hi Soorejmg,

Before spending any time on Zephir's post it might be useful to look here:-

AWT .. an invalid theory.

http://forum.physorg.com/index.php?showtop...ndpost&p=125525

-C2.
soorejmg
i dnt knw if if its wrong..But any way its confudingh..I got anice explanation from ron
Lsos
QUOTE (soorejmg+Sep 28 2006, 06:50 PM)

But what if his or my strenght was greater.Isnt it surrisin gthat these forces are balanced!!!!If mine was greater then he would come towards me and if his was greater then he would leave.Same in case of moon and earth..
How is it staying so??!!!How come earths power and moons power was balanced???!!!!!!!!!!!!!1

Someone correct me if I'm wrong on this, but the "forces" get balanced naturally. If we sped up the moon, for example, it would just move to a higher orbit. If we slowed down, it would move closer to the earth. For how fast its going, the position its in is where the "forces get balanced" as you put it.

Another way to think of orbit is to imagine getting on top of a tall tower and throwing a ball. It will fall, but away from the tower. Throw it harder, and it will fall further away. Throw it very hard and it will fall even beyond the horizon. Throw it hard enough, and it will just not fall.

Zephir
QUOTE (soorejmg+Sep 28 2006, 10:10 PM)
But any way its confusing..I got anice explanation from ron...

You obtained the description of situation from Ron, but no explanation, why the gravity attracts the moon towards the earth. From this point of view, the explanation of ron is just a partial step towards the complete understanding of situation. It's nice to see, how some people even don't understand, what all they don't understand...

Of course, if you're lucky with this stage, I'm the last person, who will take care about it... But don't forget - you're not the only persons on the Earth, who can read this forum and somebody may want to see a more deeper explanation. Beause this is not the private web site, I'm not writing here just for you, face it.
soorejmg
QUOTE (Lsos+Sep 28 2006, 07:26 PM)
Someone correct me if I'm wrong on this, but the "forces" get balanced naturally. If we sped up the moon, for example, it would just move to a higher orbit. If we slowed down, it would move closer to the earth. For how fast its going, the position its in is where the "forces get balanced" as you put it.

Another way to think of orbit is to imagine getting on top of a tall tower and throwing a ball. It will fall, but away from the tower. Throw it harder, and it will fall further away. Throw it very hard and it will fall even beyond the horizon. Throw it hard enough, and it will just not fall.

OKK...suppose there was no air in earth.Then i am standing and throughing a ball parellel to earth surface.Will the ball keeep moving around the earth??It will fall down right??(that is if it was not thrown with a force not greater than Gravitational force).But If it was thrown with a force greater than gravitational force(that is it can over come gravitational force) then it would have gone out and keep moving in a straight line right??

How did it happen that its not moving out in straight line and also not falling???!!!!Its really intersting....
soorejmg
QUOTE (Zephir+Sep 28 2006, 08:30 PM)
You obtained the description of situation from Ron, but no explanation, why the gravity attracts the moon towards the earth. From this point of view, the explanation of ron is just a partial step towards the complete understanding of situation. It's nice to see, how some people even don't understand, what all they don't understand...

Of course, if you're lucky with this stage, I'm the last person, who will take care about it... But don't forget - you're not the only persons on the Earth, who can read this forum and somebody may want to see a more deeper explanation. Beause this is not the private web site, I'm not writing here just for you, face it.

May be u are right..But i dont know...

ANY WAY WHEN SOMEONE WHO DONT KNOW THE BASICS ASKS YOU SHOULDNT EXAPLAIN IN DETAIL AND NOT TRY TO WRITE EVRYTHNIG THAT U KNOW,I LOOKED AT SOME OTHER POST TOO.I FOUND THAT U ARE SOME WAY RELATING EVERY THING TO AETHER THEORY SOMETHINGF...AND NOTHING IS CLEAR.....
soorejmg
help help help help help help help help help help help help
help help help help help help
help help help help help help
Shemi
QUOTE
But If it was thrown with a force greater than gravitational force(that is it can over come gravitational force) then it would have gone out and keep moving in a straight line right??
You are sayin if it is thrown at a velocity greater than the escape velocity right? Actually, the path of the object would be curved, it would be a hyperbola with the earth's center of mass as one of its foci.

As for the moon, there are a few theories on how it got its initial velocity:

1. A mars-sized planetoid hit the proto-earth causing about 2-3 lunar masses to be thrown into orbit. This matter would have been mostly from earth's mantle and would have "clumped" together to form the moon over about 100 years. This theory explains the moon's similar composition but lack of water and low density (mantle rock is less dense than the iron core). (this is currently the most popular theory)

2. The earth and moon could have both formed out of the same section of gas and dust/planetoids in the early solar system, much like a binary star system. This is the likely method for the formation of most other moons in the solar system.

3. The moon could have been a large passing planetoid that came too close to the earth and was captured by its gravity. That such an encounter would occur is less probable than the 1st option and would likely produce a moon with a high eccentricity (which is not observed), however, there are a few moons in the solar system that likely are moons because of this process.
soorejmg
QUOTE (Shemi+Sep 29 2006, 05:24 AM)
You are sayin if it is thrown at a velocity greater than the escape velocity right? Actually, the path of the object would be curved, it would be a hyperbola with the earth's center of mass as one of its foci.

As for the moon, there are a few theories on how it got its initial velocity:

1. A mars-sized planetoid hit the proto-earth causing about 2-3 lunar masses to be thrown into orbit. This matter would have been mostly from earth's mantle and would have "clumped" together to form the moon over about 100 years. This theory explains the moon's similar composition but lack of water and low density (mantle rock is less dense than the iron core). (this is currently the most popular theory)

2. The earth and moon could have both formed out of the same section of gas and dust/planetoids in the early solar system, much like a binary star system. This is the likely method for the formation of most other moons in the solar system.

3. The moon could have been a large passing planetoid that came too close to the earth and was captured by its gravity. That such an encounter would occur is less probable than the 1st option and would likely produce a moon with a high eccentricity (which is not observed), however, there are a few moons in the solar system that likely are moons because of this process.

optimo
It is a coincidence that the Moon started a nice orbit around Earth. If you accept the topmost theory about a large mass colided with our planet, the catalyst is that the large mass would have just the magic weight (maybe a large range) to throw off a chunk that would start a very low orbit. That was the Moon.

I would deduce that the spinning of our proto-planet contributed to the initial velocity and direction of the Moon's orbit.

You know the Moon is getting farther away from Earth? It's true!
The orbital system is not balanced perfectly yet. And the orbit is not nearly a perfect circle, as the Moon is sometimes closer or further through the year.

You can read more, as I just found out.
http://curious.astro.cornell.edu/question.php?number=124
http://curious.astro.cornell.edu/question.php?number=699

soorejmg
QUOTE (optimo+Sep 29 2006, 07:02 AM)
You know the Moon is getting farther away from Earth? It's true!
The orbital system is not balanced perfectly yet. And the orbit is not nearly a perfect circle, as the Moon is sometimes closer or further through the year.

You can read more, as I just found out.
http://curious.astro.cornell.edu/question.php?number=124
http://curious.astro.cornell.edu/question.php?number=699

The reason for the increase is that the Moon raises tides on the Earth. Because the side of the Earth that faces the Moon is closer, it feels a stronger pull of gravity than the center of the Earth. Similarly, the part of the Earth facing away from the Moon feels less gravity than the center of the Earth. This effect stretches the Earth a bit, making it a little bit oblong. We call the parts that stick out "tidal bulges." The actual solid body of the Earth is distorted a few centimeters, but the most noticable effect is the tides raised on the ocean.

Now, all mass exerts a gravitational force, and the tidal bulges on the Earth exert a gravitational pull on the Moon. Because the Earth rotates faster (once every 24 hours) than the Moon orbits (once every 27.3 days) the bulge tries to "speed up" the Moon, and pull it ahead in its orbit. The Moon is also pulling back on the tidal bulge of the Earth, slowing the Earth's rotation. Tidal friction, caused by the movement of the tidal bulge around the Earth, takes energy out of the Earth and puts it into the Moon's orbit, making the Moon's orbit bigger (but, a bit pardoxically, the Moon actually moves slower!).

I SAW THIS IN THE LINK U PROVIDED.IN THIS IT SAYS THE BULGE TRIES TO SPEED UP THE MOON.HOW IS IT??IS IT BECAUSE THE GRAVITATIONAL PULL FROM THE BULGED SIDE GIVES A SMALL PUSH TO MOON AS EARTH TURNS??I THOUGHT IT LIK THAT IS IT LIKE THAT??

Lsos
QUOTE (soorejmg+Sep 29 2006, 02:11 AM)
OKK...suppose there was no air in earth.Then i am standing and throughing a ball parellel to earth surface.Will the ball keeep moving around the earth??It will fall down right??(that is if it was not thrown with a force not greater than Gravitational force).But If it was thrown with a force greater than gravitational force(that is it can over come gravitational force) then it would have gone out and keep moving in a straight line right??

How did it happen that its not moving out in straight line and also not falling???!!!!Its really intersting....

Yes, if you threw the ball too slowly it will fall down. If you threw it just fast enough, it will still fall down, but due to the earth's curvature, the ground will fall away from it just as quickly and it will go into orbit. If you throw it faster than that...well, just look at this picture. It will help you understand what happens.

And yes, if you throw it fast enough it will just fly away...although not in a straight line. Gravity will still curve its path.
optimo
QUOTE
I SAW THIS IN THE LINK U PROVIDED.IN THIS IT SAYS THE BULGE TRIES TO SPEED UP THE MOON.HOW IS IT??IS IT BECAUSE THE GRAVITATIONAL PULL FROM THE BULGED SIDE GIVES A SMALL PUSH TO MOON AS EARTH TURNS??I THOUGHT IT LIK THAT IS IT LIKE THAT??

Yes, as you have said here, the energy from the Earth is transfered into the Moon orbit. But , it does not "speed up" persay, as a greater speed would make the orbit farther. The paradox is that the orbit takes longer to complete going once around, and this makes the period slower, the term should be `longer`.

The Moons rate of change overall will be slowing, as the Earth is also slowing.

I think you understand this now, the system is pushing and pulling and both components are in a constant exchange of momentum and energy. It is always wanting to be balanced.
soorejmg
QUOTE (optimo+Sep 29 2006, 08:07 PM)

Yes, as you have said here, the energy from the Earth is transfered into the Moon orbit. But , it does not "speed up" persay, as a greater speed would make the orbit farther. The paradox is that the orbit takes longer to complete going once around, and this makes the period slower, the term should be `longer`.

The Moons rate of change overall will be slowing, as the Earth is also slowing.

I think you understand this now, the system is pushing and pulling and both components are in a constant exchange of momentum and energy. It is always wanting to be balanced.

no..i dnt understand what u told now.....SO ISNT IT NOT MOVING AWAY???MOON NOT MIVING AWAY?
NJ Steve
uh, go to the libarary and take out a book on gravity and the soular system! misspellin' is intentional!

1. The motion of the moon started when the solar system formed many years ago.
2. Gravity, a basic force of the universe, keeps it in revolution around earth! Read Newton.

3. Moon is NOT in a stationary orbit - it is in an ever-shrinking orbit around earth. At some point in the future, the moon will collide with earth!

Palpatane
QUOTE (NJ Steve+Jan 3 2007, 07:31 PM)
uh, go to the libarary and take out a book on gravity and the soular system! misspellin' is intentional!

1. The motion of the moon started when the solar system formed many years ago.
2. Gravity, a basic force of the universe, keeps it in revolution around earth! Read Newton.

3. Moon is NOT in a stationary orbit - it is in an ever-shrinking orbit around earth. At some point in the future, the moon will collide with earth!

1) No, the moon coalesced from the debris thrown up by "the big splat," which happened a "few" years after the solar system formed.

2) No, inertia does.

3) Actually the moon is slowly moving away from the Earth.
Hottie
Just a curiosity to get y'all to think more.

could not the angular momentum of the earth around the sun also add a bit of a boost at certain times of the year, or does it balance out?
kaneda
Our Moon like the Earth is in a stable orbit around the sun but because we are so close to it, we orbit each other too.

Because it is so close, Earth's gravity is strong enough to keep one face turned to it all the time.

Year by year the Moon is literally inching away from the Earth.
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