# The Naked Scientists Forum

### Author Topic: How big does an object have to be for its gravity to make a big difference?  (Read 5900 times)

#### tommya300

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##### How big does an object have to be for its gravity to make a big difference?
« on: 22/08/2010 11:50:40 »

How big does an object have its gravity of it to make a big difference?
It was explained to me that Accretion process is not accidental it occurs buy attraction of static charges. After the static charges the material starts to gain in gravity, how big or what dimension is needed to start its gravitational attraction?
Can this be related to the material, in size, that the gravity hold the explosive forces together, before that of the big bang?
« Last Edit: 24/08/2010 00:37:59 by tommya300 »

#### Soul Surfer

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• keep banging the rocks together
##### Re: How big does an object have to be for its gravity to make a big difference?
« Reply #1 on: 22/08/2010 23:17:55 »

#### tommya300

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##### Re: How big does an object have to be for its gravity to make a big difference?
« Reply #2 on: 24/08/2010 00:36:14 »
I have rewrote the question
« Last Edit: 24/08/2010 00:40:01 by tommya300 »

#### tommya300

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##### How big does an object have to be for its gravity to make a big difference?
« Reply #3 on: 24/08/2010 20:41:26 »
Is there a certain dimension for mass to experience gravity.

#### Vern

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##### How big does an object have to be for its gravity to make a big difference?
« Reply #4 on: 24/08/2010 21:00:40 »
No, mass of any size experiences gravity. In fact, the lowly photon, the least significant thing we know about, both gives off gravity and responds to it.

#### tommya300

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##### How big does an object have to be for its gravity to make a big difference?
« Reply #5 on: 24/08/2010 21:41:29 »
No, mass of any size experiences gravity. In fact, the lowly photon, the least significant thing we know about, both gives off gravity and responds to it.

So was I misinformed about the Accretion process was due to static clinging and it was gravity right from the start of the accretion process?

If I was not misinformed,  then combinding your post with what was told to me, how large does the mass have to be for the gravitational effect take over the static clinging?
.
« Last Edit: 24/08/2010 21:48:40 by tommya300 »

#### Soul Surfer

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##### How big does an object have to be for its gravity to make a big difference?
« Reply #6 on: 24/08/2010 23:22:42 »
Localised atomic forces help grains to stick together and accrete into lumps big enough for gravity to have an effect to form planets  cool gas clouds can also collapse under their own gravity to form stars.

#### tommya300

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##### How big does an object have to be for its gravity to make a big difference?
« Reply #7 on: 25/08/2010 02:18:20 »
.
Localised atomic forces help grains to stick together and accrete into lumps big enough for gravity to have an effect to form planets  cool gas clouds can also collapse under their own gravity to form stars.

Cool!
Now what is the dimension of the accrete into lumps big enough for gravity to have an effect
Is there a numerical value like, I am just guessing, 500km in diameter or some resonable number that lump is big enough for gravity to have that effect.
.

#### Soul Surfer

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• keep banging the rocks together
##### How big does an object have to be for its gravity to make a big difference?
« Reply #8 on: 25/08/2010 18:25:07 »
No,  500 km is the size that gravity is strong enough to force objects to become approximately spherical.  Gravity will help things to hold together much smaller than this, probably a lot less than 1km maybe a few tens of metres.

#### tommya300

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##### How big does an object have to be for its gravity to make a big difference?
« Reply #9 on: 26/08/2010 15:52:35 »
I guess we each have an estimation of a specific catagory of what makes a big difference.
Thanks Soul Surfer for your information

#### tommya300

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• Posts: 655
##### How big does an object have to be for its gravity to make a big difference?
« Reply #10 on: 27/08/2010 13:54:43 »
.
Localised atomic forces help grains to stick together and accrete into lumps big enough for gravity to have an effect to form planets  cool gas clouds can also collapse under their own gravity to form stars.

Cool!
Now what is the dimension of the accrete into lumps big enough for gravity to have an effect
Is there a numerical value like, I am just guessing, 500km in diameter or some resonable number that lump is big enough for gravity to have that effect.
.

No, big enough to form planets or stars.
An atom or,as Vern said, a photon 'has' gravity, but is extremely weak that it is negligible.

Everyone else had said that a photon has no mass and does not have a gravitational field???
What values are they if that is incorrect? Where is this certified documentation that supports this characteristic of a photon.

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##### How big does an object have to be for its gravity to make a big difference?
« Reply #10 on: 27/08/2010 13:54:43 »