Originally posted by CLPrime
This restraining force is called the Normal force, and it's mostly found in high school physics.edit on 6-5-2012 by CLPrime because: (no reason given)
Originally posted by Jukiodone
Why is gravity so week,
why does gravity only pull ( it doesnt seem to have an anti mechanism)
What is the instantaneous action at distance, what mediates gravity- is there a Graviton???
BTW I;d be interested to hear from the resident Gravity experts on exactly which dimension the (Already 3 Dimenisonal) Planet seems to sag in to create the "gravity well " in the Euclidian geometery expalantion as shown in jiggerj's pic...we seem to have a 3d object with its own x,y,z coordinates moving through another dimension whilst alos affecting another 3d object ??
Originally posted by CLPrime
reply to post by jiggerj
The Sun warps space out to an infinite distance. This warping approximately follows the inverse square rule: at twice the distance, the force of gravity is 1/4 as strong.
Neptune is 30 times further out from the Sun than the Earth is. That means, at that distance, the force of gravity is 1/(30^2) = 1/900 the strength it is here.
If you know what a force is, you'll know that it's the amount of "push" needed to accelerate a certain mass by a certain amount: F = ma, where F is the force in Newtons, m is the mass in kg, and a is the acceleration of the mass in m/s^2.
Also, you should keep in mind that it is a force that keeps a planet in orbit - specifically, centripetal (center-seeking) force. Even more specifically, that centripetal force here is the gravitational pull of the Sun.
So, the force at the distance of Neptune is 1/900 the strength it is here at the distance of the Earth. That's the centripetal force that holds Neptune in its orbit.
Recalling that F = ma, rearranging that gives the acceleration as a = F/m. That means the centripetal acceleration of the orbiting planet is proportional to the force of gravity at that distance. At the distance of Neptune, then, the centripetal acceleration is much less than it is at the distance of the Earth.
Now, centripetal acceleration is equal to (v^2)/r, where v is the orbital velocity of the planet and r is its distance from the Sun. Orbital velocity is proportional to the square-root of the centripetal acceleration. That means that the orbital velocity of Neptune will be proportional to the square-root of 1/900, or 1/30, as compared to the orbital velocity of the Earth.
Ultimately, this is what I'm getting at: the only thing that must be satisfied in order to keep Neptune in an orbit around the Sun is that particular orbital velocity. Any slow and it falls into the Sun; any faster and it will fly off into space.
You will find that this is true by checking the orbital velocity of Neptune as compared to the Earth. For the Earth, it's 30 km/s; for Neptune, it's 5.43 km/s. The fact that Neptune's orbital velocity isn't exactly 1/30 that of the Earth is because it's more massive. If the Earth suddenly found itself out at the distance of Neptune, its new orbital velocity will be exactly 1/30 what it is now, which would just happen to be 1 km/s.
As I said, the gravity well of the Sun extends out to infinity. Any object, even one millions of light-years away, can conceivably enter into an orbit around the Sun. However, at that distance, too may other stars get in the way.
Originally posted by Jukiodone
I'd be interested to hear from the resident Gravity experts on exactly which dimension the (Already 3 Dimenisonal) Planet seems to sag in to create the "gravity well " in the Euclidian geometery expalantion as shown in jiggerj's pic...we seem to have a 3d object with its own x,y,z coordinates moving through another dimension whilst alos affecting another 3d object ??edit on 6-5-2012 by Jukiodone because: (no reason given)
Originally posted by CLPrime
reply to post by ImaFungi
I'm not sure what part of the Gravitron is supposed to relate with gravity. I can't see any obvious similarity.
Originally posted by ImaFungi
if all the celestial bodies of the universe were paused as they are, and there was no movement yet time traveled on, would there still be such a thing as gravity?
I pictured the gravitron as similar to the planet,,,, if the gravitron was rotating and traveling as a body through space, i imagine it is similar to why tiny things compared to the planet are destined to not travel far from the surface.
Originally posted by artistpoet
Originally posted by intrptr
Einsteins theory of relativity involved that very premise of gravity bending light. A huge effort was undertaken to capture that effect during succeeding eclipses. They were ultimately successful and the proof was determined with just the distance from the earth to the sun. About 92 million miles. I don't have a link for all that just now... if someone already mentioned it please forgive me. The light traveling throughout the Universe has been bent around so many times I wonder if the actual size of it is much smaller. We just think that is a different part of space but really we are just seeing ourselves from a different angle? Dunno...
Einstein Ring
Thanks for link - Also there is the Einstein Cross
This is created when one distant galaxy or quasar aligns behind another causing 5 light sources to appear - One central light and 4 on quadrants
en.wikipedia.org...
Sure, I'd like all those questions answered. But I still want to know how the sun can have any affect whatsoever on a cosmic body billions and billions of miles away.
Originally posted by CLPrime
reply to post by jiggerj
The Sun warps space out to an infinite distance. This warping approximately follows the inverse square rule: at twice the distance, the force of gravity is 1/4 as strong.
The stars in the disk of "ordered" galaxies seem to stay "apart" relative to each other. Is that an accurate description? What is the force that maintains distance spacing of suns, despite gravity.
This is not a la grange question. And if we take a string and swing a stone around our heads, is that another way to describe gravity that excludes the warping of space explanation? Gravity well is an analogy, right? That gravity could be a "string" of sorts between objects with deference to the larger masses? And lastly, my underedumacatedist question of them all, I have seen astronauts eat globs of water until I thought I was going to throw up, but never seen them swing a ball on a string around their head. Is that possible In free fall?
What is the medium that keeps the stars separate from each other in a galaxy?
Originally posted by intrptr
The stars in the disk of "ordered" galaxies seem to stay "apart" relative to each other. Is that an accurate description? What is the force that maintains distance spacing of suns, despite gravity. This is not a la grange question.
And if we take a string and swing a stone around our heads, is that another way to describe gravity that excludes the warping of space explanation? ... That gravity could be a "string" of sorts between objects with deference to the larger masses?
Gravity well is an analogy, right?
And lastly, my underedumacatedist question of them all, I have seen astronauts eat globs of water until I thought I was going to throw up, but never seen them swing a ball on a string around their head. Is that possible In free fall?
Originally posted by CLPrime
reply to post by artistpoet
There is no medium in which matter exists. Space is the volume that contains all matter...it's not a medium, it's a region. And a vacuum is the lowest possible energy state of a space.
Originally posted by CLPrime
reply to post by artistpoet
There is no medium in which matter exists. Space is the volume that contains all matter...it's not a medium, it's a region. And a vacuum is the lowest possible energy state of a space.