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I had a confusion regarding Einstein's theory of gravity.. what confuses me is that if spacetime is warped and every mass curves the space time which causes lighter masses to stick to the heavier mass than why does'nt the lighter masses fall away due to inertia while the heavier mass moves away.. For instance take the example of earth and the gravity.. If we are attached to earth due to gravity which is created because of th earths warping the space. than why dont we fall away due to inertia when the earth orbits arround the sun.. i mean should'nt we be at the initial position when the earth moves away??
I beat you!
There is a minor problem when we move to the equator of the the rotating earth, at present the rotational speed is rather low but if it was much greater we would certainly fall off.
Quote from: DoctorBeaver on 23/08/2007 13:05:34I beat you! It's not fair: you write (correct) english faster than me! [B)]
I thought that 'centrifugal force' was a rather muddled concept and that what was really happening was that the body trying to sit on the equator of the fast rotating Earth was trying to move in a straight line as dictated by its inertia and that the Gravity of the Earth was insufficient to deflect it from that path, hence it flies off.
I may be faster at typing, but your English is better than a lot of English people I know.
was that the body trying to sit on the equator of the fast rotating Earth was trying to move in a
And here's another rant. If people use the term 'inertia', what are its units? I have never seen them defined. No units means you can't measure it. That means it's not really a part of Physics.Any views?
Quote from: sophiecentaur on 24/08/2007 16:19:20And here's another rant. If people use the term 'inertia', what are its units? I have never seen them defined. No units means you can't measure it. That means it's not really a part of Physics.Any views?According to equivalence principle, a gravitational field is equivalent to an inertial field. Centrifugal force is an inertial field, so it exists as well as a gravitational field.(Is it me or I have a "Deją vu"?)
Isn't a gravitational field equivalent to an accelerating inertial frame?
OK folks - just show me the text book where the units of 'inertia' are listed.As far as I'm concerned 'inertia' is the thing that keeps me in bed in the mornings.I just can't see the point of using it when discussing Physics. Don't we have enough well - defined variables?Surely the definition of an inertial field is one where there is NO acceleration. Ohmygod here we go again, as you say.
Yes - you are right. The red mist was coming down and I used the wrong term.Inertia seems to be used in hand waving arguments to stand for something half way between mass and momentum.Certainly, in classical Physics, you need never use the word at all. And, before anyone starts to hold forth on SR or GR, they should first have a decent grasp of Newtonian stuff - it's an excellent start and sorts out the men from the boys (or the gender-free equivalent).