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Offline tamo kangujam

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gravitational force
« on: 17/02/2014 10:09:50 »
how does earth has magnetic power or gravitational power? will the other planets also has the same with the same direction and field lines? if so what could be the north pole and south pole of the universe?


 

Online evan_au

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Re: gravitational force
« Reply #1 on: 17/02/2014 11:00:37 »
The Earth has a gravitational field, just as any other mass like an asteroid, a planet, a star or a galaxy. The Earth's gravitational field will remain intact as long as the Earth remains intact.

The Earth also has a magnetic field. This is thought to be due to convection of molten metal in the center of the Earth. This is not a stable field, but one that changes chaotically in direction and polarity over long periods of time. The current "dynamo" is expected to stop working when the molten core cools down, leaving an extremely weak magnetic field, like the Moon. Other bodies like the Sun, Jupiter and Neutron Stars also have strong magnetic fields, pointing in different directions, and produced by different mechanisms than the Earth.

You cannot use a gravity or magnetic field as a permanent source of power.

If you look at photos of galaxies in the sky, the axis if the different galaxies is somewhat random. So there doesn't seem to be an obvious North and South pole for the universe as a whole.
 

Offline tamo kangujam

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Re: gravitational force
« Reply #2 on: 18/02/2014 05:44:07 »
Thank you Evan.
So, the gravitational force of the earth is due to the presence of molten metals, right? Then why are those non-metallic materials got attracted by the earth's gravitational force? Also according to Newton, every particle attracts every other particles(even those non-me talic) how this will be possible?
« Last Edit: 18/02/2014 05:53:16 by tamo kangujam »
 

Offline snowyco

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Re: gravitational force
« Reply #3 on: 21/02/2014 18:21:10 »
Thank you Evan.
So, the gravitational force of the earth is due to the presence of molten metals, right?

Yes, the gravitational force of the earth is due to the presence of molten metals   plus    all the other mass and material and energy   in  and  on  earth.     This means that the molten metals contribute to earth's gravity, but are not the sole source of earth's gravity.


Then why are those non-metallic materials got attracted by the earth's gravitational force? Also according to Newton, every particle attracts every other particles(even those non-me talic) how this will be possible?

Correct (about Newton),  every particle   and   every photon  (referring to your other question on the wave and particle natures of light)   have  mass,   and hence    they all attract each other.     This is why the great mass of our sun   measurably   bends  starlight   that passes near it.

The cause of attraction between particles of matter and also attraction between light and matter is currently a great mystery.   Some scientists have calculated that sub-atomic  things  they call  "gravitons"  may exist and may cause gravity, but this has been neither proven nor disproven.   Maybe you will find a way to prove it or disprove  the existence of gravitons    someday.

Science is such a fun place,  because the deeper we dig,  the more we realize just how much we  don't  know.    Scientists make it seem like they know a lot,  by providing a lot of quick answers to our questions.    But in reality,   we have more questions than answers,  and what we know  and   what we can measure   is not even 1% of what exists.    For Example:  Dark energy is thought to make up 68% of the universe,   and   dark energy + dark matter together are now thought to make up 96% of the universe.   So stuff we  cannot see   and cannot measure   is what we  think  most of the universe is made of.

Scientists, like Evan had no idea of either dark matter nor dark energy just 30 years ago,   which means they thought they knew about gravity and light and matter,   but in reality,   they knew  about less than 4%  of what was around them.

All of this   not-knowing    can be simultaneously  exciting  and  humbling,  especially when it pushes us to work to figure out the what's and why's of the world.   

So, when your science teacher  or professor  or   some person on the internet   tells you:   "This is what ..."     or    "This is why..."    Instead, know they are just making their best  guesses  based on observations and hypotheses (opinions),  and  smile inside, because you know that we   will  likely know   much more,  and possibly have very different understandings  in just a few more years.
« Last Edit: 21/02/2014 18:26:08 by snowyco »
 

Offline alancalverd

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Re: gravitational force
« Reply #4 on: 21/02/2014 18:44:14 »
So, the gravitational force of the earth is due to the presence of molten metals, right?

No. The gravitational field is due to the presence of everything that has mass. It attracts anything else that has mass.

The metallic core of the earth provides a magnetic field which is entirely independent of the gravitational field. It attracts other para- or ferro-magnetic materials and repels diamagnetic materials.

A lump of lead has a measurable gravitational field but no magnetic field. The two phenomena are not the same.
 

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Re: gravitational force
« Reply #4 on: 21/02/2014 18:44:14 »

 

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