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![[Post New]](/templates/default/images/icon_minipost_new.gif) 26 Mar 2008 22:35:05 IST
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why planets revolve around the stars in elliptical orbits?
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26 Mar 2008 22:51:23 IST
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 elliptical orbits ..i think is a result of simple geometry..!!! ellipse..locus of a pt.. wic moves such tht sum of distances from two fixed pts is constant...sun is at one of the focii of tht ellipse. now why ellipse..?? actually earth experience no torque due to rev. around sun.. thus ang. momentum is conserved.. it follows tht angular velocity * moment of inertia arnd axis is constant..
it now follows tht areal velocity (dA/dt) is constant..
that can only happen wen locus of the earth is an ellipse... as in an ellipse dA/dt is constant..  |
Diamonds r formed under greatest pressures..
so r the champs.
Kriteesh..
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26 Mar 2008 22:54:17 IST
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the plants revolvs around the sun because force of attrection b/w planets & sun produced centripital forec. Due to centripital force the planents revolvs around the sun.
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26 Mar 2008 23:01:29 IST
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motion of planets around the sun is limited by conservation of angular momentom. The most general trejectory on which angular momentom is conserved is eliptical.
I don't mean that the cuase of motion of planet around is just due to coservation of angular momentom.It is the gravitational force.
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26 Mar 2008 23:41:04 IST
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Because of coservation of angular momentom. But if ask why the angular momentom is conserved I don't have anyanswer. I don't think such questions are easy to answer even with physics.
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27 Mar 2008 00:18:15 IST
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no motion in 3d space is ACTUALLY circular.
IT can only appear to be so within certain frames of reference.
it is because in nature, forces never exactly balance out each other which is why a perfectly circular path doesn't REALLY exist.
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30 Mar 2008 17:54:07 IST
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Consider a particle of mass m at a distance of r from another heavy particle of mass M. If we give it a tangential velocity v then
(i) It will fall into M if v(ii) Will move in circle if v= sqrt(GM/r)
(iii) Will move in ellipse if sqrt(GM/r)(iv)Will move in parabola if v= sqrt(2GM/r)
(v)Will move in hyperbola if v> sqrt(2GM/r)
So planets move in eleptical orbit because at there nearest point to sun there velocity is slightly greater than sqrt(GM/r)
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Krishna Gopal Singh
B.Tech Chemical Engg
IIT Delhi 2002
Currently doing PhD from IIT Delhi |
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