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Member (Idle past 2955 days) Posts: 706 From: Joliet, il, USA Joined: |
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Author | Topic: gravity | |||||||||||||||||||||||||||||||
shadow71 Member (Idle past 2955 days) Posts: 706 From: Joliet, il, USA Joined: |
I am relativity new on the board and was wondering if there have been any threads on the subject of gravity.?
My question is, are there any theories as to How Gravity come into existence? Was there some evolutionary sequence? Did it just come into existence with the Big Bang? Is it natural or metaphysical? Would appreciate any input from informed people on this board.
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AdminPhat Inactive Member |
Thread copied here from the gravity thread in the Proposed New Topics forum.
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AZPaul3 Member Posts: 8529 From: Phoenix Joined: Member Rating: 5.1 |
Start with some basic research first.
Here When you have questions outside the most basic come on back. There is a lot of knowledge on the subject in the membership.
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Dogmafood Member (Idle past 370 days) Posts: 1815 From: Ontario Canada Joined: |
From your link
quote: and
quote: If the attractive force of gravity is proportional to the mass of two bodies, why does an object of greater mass not fall quicker?
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Dr Adequate Member (Idle past 306 days) Posts: 16113 Joined: |
If the attractive force of gravity is proportional to the mass of two bodies, why does an object of greater mass not fall quicker? Because it takes proportionally more force to accelerate a more massive object. Edited by Dr Adequate, : No reason given.
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AZPaul3 Member Posts: 8529 From: Phoenix Joined: Member Rating: 5.1 |
If the attractive force of gravity is proportional to the mass of two bodies, why does an object of greater mass not fall quicker? Your talking about two objects falling in earth's gravity well. There is a third body in there: the earth. Each dropped object is in free fall within earths gravity well. Each object will drop with the same acceleration. That is the Acceleration of Gravity. The proportional mass part comes in from the mass of object 1 (an apple) vis-a-vis the earth, totally independent of the mass of the other dropped object (a sledge hammer). Both exert an attractive force on the other but since the earth is much more massive the force of the apple on the earth is negligible while the force of the earth on the apple is considerable thus the earth moves the apple further, but not faster, than the apple moves the earth. The same for the 15 lb sledge hammer. The sledge is exerting a more powerful force on the earth than the apple did due to its greater mass but is still negligible considering the difference in mass between it and the earth thus the earth is also moving the heavier sledge further, but not faster, than the sledge moves the earth. If all you had in the universe were the apple and the sledge hammer then the two would each exert a force on the other with the sledge having the greater force thus moving the apple further, but not faster, than the apple moves the sledge.
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Dogmafood Member (Idle past 370 days) Posts: 1815 From: Ontario Canada Joined: |
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NoNukes Inactive Member |
If all you had in the universe were the apple and the sledge hammer then the two would each exert a force on the other with the sledge having the greater force thus moving the apple further, but not faster, than the apple moves the sledge. Maybe I am misreading this, but your comment seems off. The gravitational force exerted on the earth by the moon is exactly equal and opposite to the gravitational force exerted on the moon by the earth. The resultant accelerations on the two bodies are different. The result is that the two objects orbit the moon-earth barycenter which is located inside the earth. The moon moves both farther and faster than the earth due to their mutual gravitational attraction. Two objects of different masses falling towards earth experience the same acceleration because despite experiencing different forces proportional to their respective masses, each object resists accelerating in response to force due to its inertia, with said inertia also being proportional to its mass. So the heavier object receives a larger force, but since a =F/m, the larger force results in the same acceleration generated by the smaller force on the smaller object. Edited by NoNukes, : No reason given.Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison. If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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NoNukes Inactive Member |
Gravity is a phenomenon that results from the curvature of space-time. It likely existed at every moment after the big bang when there was any energy and any time and space.
I'd say that it is natural, but then I don't know what it would mean to call it metaphysical. Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison. If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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NoNukes Inactive Member |
If the attractive force of gravity is proportional to the mass of two bodies, why does an object of greater mass not fall quicker? If you wanted a huge big rock to accelerate the same as a small one, would you use a smaller or larger force on the big rock? Remember F=ma.Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison. If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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petrophysics1 Inactive Member |
The force between objects is given by
F=Gx m1m2/d^2 ,G is a constant I'll just say it's 1. d=1 m2=10,000 Let's look at two cases, one where m1=1 and one where m1=0.1 Case 1, F=Gx m1m2/d^2=1x 1x10,000/1^2= 10,000 Case 2, F=Gx m1m2/d^2=1x 0.1x10,000/1^2= 1,000 So in case 1 the force of gravity=10,000 and in case 2 the force of gravity=1000.............BUT Since F=ma the acceleration a=F/m case 1, a=F/m=10,000/1=10,000 case 2, a=F/m=1000/0.1=10,000 WOW, look at that, even though case 1 is 10 times the mass of case 2, they both have the same acceleration. I guess they will fall the same which answers your question.
If the attractive force of gravity is proportional to the mass of two bodies, why does an object of greater mass not fall quicker? P.S. It appears to me many people don't understand F=ma, this means that if you apply a CONSTANT force to an object it will go faster and faster. When people push a heavy object, after they overcome the force of friction, they "think" they are applying a constant force and the object isn't going faster and faster. So F=ma doesn't seem right, but they actually slack up a bit and ARE NOT applying a constant force. It's why people think Newton was a genius. Edited by petrophysics1, : No reason given. Edited by petrophysics1, : add P.S. Edited by petrophysics1, : spelling
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shadow71 Member (Idle past 2955 days) Posts: 706 From: Joliet, il, USA Joined: |
My question is, are there any theories as to How Gravity came into existence?
Sorry for the typo in OP.
NoNukes writes:
I'd say that it is natural, but then I don't know what it would mean to call it metaphysical. My question goes to the beginning of gravity. I cannot find any accepted theories as to how gravity came into existence.Most say it is a natural phenomenon but give no scientific support for that position. Have been reading Gerald Schroeder and he leaves me with the impression gravity is metaphysical in origin.
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Dogmafood Member (Idle past 370 days) Posts: 1815 From: Ontario Canada Joined: |
Remember F=ma. Well yes now I do remember it. I also have some vague recollection of having graduated from high school. I have a mind like an etch-a-sketch. While this keeps things fresh and interesting I sometimes feel like I have covered this ground before.
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AZPaul3 Member Posts: 8529 From: Phoenix Joined: Member Rating: 5.1 |
Maybe I am misreading this, but your comment seems off. Then it probably is. But no matter. There was a Rocky & Bullwinkle where Dudley Do-Right jumps from the bath and runs down the street yelling "Y-rika" instead of U-rika. The voice over explained that it was OK since Dudely know what he ment. I claim the same privilege.
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NoNukes Inactive Member |
When people push a heavy object, after they overcome the force of friction, If friction is present, then you do have to apply a constant force just to keep an object moving at constant velocity.Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) The apathy of the people is enough to make every statue leap from its pedestal and hasten the resurrection of the dead. William Lloyd Garrison. If there is no struggle, there is no progress. Those who profess to favor freedom, and deprecate agitation, are men who want crops without plowing up the ground, they want rain without thunder and lightning. Frederick Douglass
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