Question about gravity.

Gravity is a gradiant differential. The better question is about its nature is how does it differ from the property of an electric field.

Gravity is a gradiant differential. The better question is about its nature is how does it differ from the property of an electric field.

Originally posted by hellobruce

Originally posted by spy66
If there is gravity the vacuum column should have a specific weight.

Why do you think that?

Ok. If the column was open to atmosphere. The column down to earth's center would have a specific weight. It would have a total sum from Top atmosphere to earths center.

True vertical depth from top atmosphere to earth center x densety x 9.981. This will give you the weight of the column from top to bottom.

At the top of earths atmosphere you would have 0 weight. Just put a scale up there and try. As you come closer to earths surface the weight of the atmosphere will encrease. At surface the atmosphere weights 1 bar.

The weight of our atmoshere gives weight/presure to earths surface. If you pick up a rock, you measure how much that rock weigh in 1 bar atmosphere. You can say that the weight of the atmosphere push the rock down.

In a vacuum what would push a 10kg weight down towards earths center?

If the tunnel was open to atmosphere in both ends going from N to S. The 10 kg weight would end up in the senter in the end. The weight would accelerate down until it reached the center point. And start to slow down becaue of the weight of the column of atmosphere working down on the other end of the center point.

reply to post by spy66


You are neglecting the earth mass. Look here en.wikipedia.org...-0

Mathematical solution: www.math.purdue.edu...

reply to post by moebius


Your link is actually wrong. Gravity trains are impossible and will not act as you see in the animation.

Although they mention that they are ignoring friction, they also seem to be ignoring the gravitational pull acting above the object when it is falling down.

When the object is 1/4 through the Earth, that is 1/4 of Earth's mass above it pulling the object up, and 3/4 of the Earth's mass below it pulling it down. When the object is 1/2 through the Earth, that is 1/2 of Earth's mass pulling it one direction, and another 1/2 pulling it the other direction. The object would slow down tremendously every time it passes the 1/2 point, acting like friction. (These numbers are just an example)

Over time it would come to rest in the center.

Originally posted by spy66
In a vacuum what would push a 10kg weight down towards earths center?

Do you seriously think you are pulled to Earth because of the weight of the air above you?

Do you know what gravity is?

reply to post by illuminated0ne

Do you have any formal physics education? The question asked here is typical physics freshmen homework. One is usually asked to derive the equation for the force and eventually the oscillation period of the weight. What you have there is a harmonic oscillator. Read up on its origins, a scientist named Hooke proposed it first. My above post contains the link to the math involved.

reply to post by spy66


it would do the same thing it would do if it was not sealed. Stop in the middle of the core. And fast it would fall to the middle not because their is no friction but because the vaccum would cause an extremely hard pull

Originally posted by moebius
reply to post by spy66

 

You are neglecting the earth mass. Look here en.wikipedia.org...-0

Mathematical solution: www.math.purdue.edu...

Earths mass will have no effect on the atmosphere inside the tunnel. Because earths mass is not inside the tunnel, it is surrounding the tunnel.

It is not earth's mass that is pulling us down. It is the atmosphere. It is the weight that is above us.

If you fill a bucket with sand and lift it above your head. It will be the bucket of sand + the atmosphere that pull you down. If you step on to a scale you will notise that your weight will be: your weight pluss the bucket of sand.

If you measure the weight at earth center from where you stand. You have to add the column of mass from the center and to where you stand. Than on top of that you have to add your weight + atmosphere.

Because the scale at earths center will read:

1. The column of mass resting on the scale to the surface.
2. Your weight. Because you are standing on surface.
3. The atmospheric pressure of 1 bar. Because it is pushing down on earth surface.

reply to post by spy66

Ok. What is the weight of the vacuum column at earth's center? If there is gravity the vacuum column should have a specific weight. What is it?

Maybe i am missing something here. But I thought that a vacuum was pretty empty. It would have a a weight if it was open to the atmosphere. But its not because it is a vacuum..

reply to post by spy66

Have you actually take a look at the link I've posted.

I am not sure if I can help you as you seem to be seriously confused about gravity. Gravity is not caused by the weight of atmosphere above you. Gravity doesn't have a preferred direction(for symmetric objects and point masses). Even if you were positioned outside of the atmosphere at any position next to earth you would still experience gravitational forces towards earth center, as do the satellites and the moon.

What do you think keeps the atmosphere attached to the earth in the first place?

Originally posted by purplemer
reply to post by spy66

 

Ok. What is the weight of the vacuum column at earth's center? If there is gravity the vacuum column should have a specific weight. What is it?

Maybe i am missing something here. But I thought that a vacuum was pretty empty. It would have a a weight if it was open to the atmosphere. But its not because it is a vacuum..

correct.

Originally posted by scubagravy
The 10kg weight would make it 73% of the way before returning to the centre. Plain and simple.

You win. momentum would take it only so far out the other side.
gravity would slow it down on the other side.
smaller and smaller until zero at the center.

a vacuum is just empty space.
NOT empty gravity or momentum.
if that was so. when you drop some thing in a vacuum it would not move.

any one ever see the experiment
a lead ball and a feather are dropt in a vacuum.
they both land at the same time.
Air friction...
any one ever go to school? to much Science fiction.

Originally posted by spy66
If you fill a bucket with sand and lift it above your head. It will be the bucket of sand + the atmosphere that pull you down

No it will not, you forget that as the atmophere is under the bucket as well it will have zero effect.

3. The atmospheric pressure of 1 bar. Because it is pushing down on earth surface.

No it will not, atmospheric pressure does not push you down

Originally posted by moebius
reply to post by spy66

 

Have you actually take a look at the link I've posted.

I am not sure if I can help you as you seem to be seriously confused about gravity. Gravity is not caused by the weight of atmosphere above you. Gravity doesn't have a preferred direction(for symmetric objects and point masses). Even if you were positioned outside of the atmosphere at any position next to earth you would still experience gravitational forces towards earth center, as do the satellites and the moon.

What do you think keeps the atmosphere attached to the earth in the first place?

Earth is surrounded by a atmosphere. If earth is surrounded by atmosphere, where to you think center mass would be? It is self explaining.

All the gasses that make up our atmosphere have weight, that is a damn good clue that explains why our atmosphere have a specific distance from earth's surface and up. You need to understand all this before you start to lecture me about gravity.

As soon as a satelit comes in contact with particles from our atmosphere. The part that comes in contact with these particles will gain weight. That is how a satelite gets pulled into our atmosphere.

reply to post by spy66


Sorry, but this is absolute nonsense! Calculate atmospheric pressure and gravity at some 200-300 km distance from earth surface. And what about the moon? Or does it not exist in your reality. Ever heard of vacuum chambers? How comes that things don't start to float while being in such a chamber?

Or are you simply trolling here?

As soon as a satelit comes in contact with particles from our atmosphere. The part that comes in contact with these particles will gain weight. That is how a satelite gets pulled into our atmosphere.

No, it will cause friction, this will bleed the speed from the satellite. When it loses enough speed it will start falling into, rather than around, the planet.

The atmosphere has no effect on the mass of the satellite or the force gravity is exerting upon it.

Maybe it would help for you to look at it from the point of Potential and Kinetic energy. If you subtract out the negligible effects of the masses acting from all directions, you're back to the "center of gravity" concept (that I mentioned in an earlier post that folks just skimmed right on over). It moves toward the center of the earth due to Potential energy being converted to Kinetic energy and from the center to the other pole by converting the Kinetic to the Potential.

Even if you made the tube a mile above the surface of the earth, if it's a vacuum without the effects of atmospheric drag or friction in any way, the weight is going to move to the other end of the tube due to that interaction.

Originally posted by spy66
As soon as a satelit comes in contact with particles from our atmosphere. The part that comes in contact with these particles will gain weight. That is how a satelite gets pulled into our atmosphere.

Good grief, you really think that is why satellites that hit the atmosphere eventually fall to earth? They get heavier?

It is very obvious you are clueless about basic physics and orbital mechanics.

Originally posted by spy66

As soon as a satelit comes in contact with particles from our atmosphere. The part that comes in contact with these particles will gain weight. That is how a satelite gets pulled into our atmosphere.

ummmm.... no.....
The satellite is inclined to move off in a straight path but gravity produces a centripetal force that keeps it in orbit. There is an orbital zone based on the size of the satellite and the inertia it has....