The proof of mass vector.
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From: jamesahart79 on 14 Dec 2006 14:50 crank_hunter(a)yahoo.com wrote: > Eric Gisse wrote: > > yen, ka-in wrote: > > > In three dimensional vector algebra, area HAS TO be a vector, > > > and we can divide an area vector of a rectangle by the length > > > vector of this rectangle. > > > > Look who fails vector analysis again! > > > > [...] > > Eric Gisse is marked by Crank Alert: > > http://groups.google.gr/group/sci.physics.relativity/tree/browse_frm/thread/4841325a3c938f44/01b8793b2b1f235b?rnum=311&hl=en&_done=%2Fgroup%2Fsci.physics.relativity%2Fbrowse_frm%2Fthread%2F4841325a3c938f44%3Fscoring%3Dd%26hl%3Den%26&scoring=d#doc_01b8793b2b1f235b > > "F = ma, F = GmM/r^2. > m*dr^2/dt^2 = GmM/r^2 > r^2 * dr^2/dt^2 = GM > > The rest is left as an exercise. Do you know how to solve an ODE? > I'll give you a hint: > http://mathworld.wolfram.com/EulerDifferentialEquation.html " > > > http://groups.google.gr/group/sci.physics.relativity/tree/browse_frm/thread/6656e57a32f8da73/8de1d639d237c151?rnum=91&hl=en&_done=%2Fgroup%2Fsci.physics.relativity%2Fbrowse_frm%2Fthread%2F6656e57a32f8da73%3Fscoring%3Dd%26hl%3Den%26&scoring=d#doc_18b28dea41093521 > > "A rocket fired from inside a train that is moving with constant > velocity is an inertial frame - it doesn't accelerate, and is thus > inertial. " > > Crank Alert is a free service by Crank Hunter I'm guessing this is "Mike" again. Everyone who's been following this group knows that Eric admitted it was a mistake. Bringing it up repeatedly, without context and without including the public correction, is a form of lying. In fact, it should never be brought up again. Anyone can make a mistake. Cranks never admit to making them. Real scientists do admit their mistakes---but refuse to admit mistakes when they have, in fact, not made them...
From: Ka-In Yen on 15 Dec 2006 07:50 Eric Gisse wrote: > Phineas T Puddleduck wrote: > > In article <1165969633.567611.103040(a)j72g2000cwa.googlegroups.com>, > > "Ka-In Yen" <yenkain(a)yahoo.com.tw> wrote: > > > > > > > > Phineas T Puddleduck wrote: > > > > In article <1165882744.955562.213440(a)j72g2000cwa.googlegroups.com>, > > > > "yen, ka-in" <yenkain(a)yahoo.com.tw> wrote: > > > > > > > > > In three dimensional vector algebra, area HAS TO be a vector, > > > > > and we can divide an area vector of a rectangle by the length > > > > > vector of this rectangle. > > > > > > > > Area vectors can only be defined for flat surfaces. > > > > > > Yes, and calculus can help you work on curvy surfaces. > > > > So how are you going to define an area vector for a curved surface Please refer to Gauss's law. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/gaulaw.html > > Here comes the fun part. > Do you prepare to learn?
From: Randy Poe on 15 Dec 2006 09:34 Ka-In Yen wrote: > Eric Gisse wrote: > > Phineas T Puddleduck wrote: > > > In article <1165969633.567611.103040(a)j72g2000cwa.googlegroups.com>, > > > "Ka-In Yen" <yenkain(a)yahoo.com.tw> wrote: > > > > > > > > > > > Phineas T Puddleduck wrote: > > > > > In article <1165882744.955562.213440(a)j72g2000cwa.googlegroups.com>, > > > > > "yen, ka-in" <yenkain(a)yahoo.com.tw> wrote: > > > > > > > > > > > In three dimensional vector algebra, area HAS TO be a vector, > > > > > > and we can divide an area vector of a rectangle by the length > > > > > > vector of this rectangle. > > > > > > > > > > Area vectors can only be defined for flat surfaces. > > > > > > > > Yes, and calculus can help you work on curvy surfaces. > > > > > > So how are you going to define an area vector for a curved surface > > Please refer to Gauss's law. > > http://hyperphysics.phy-astr.gsu.edu/hbase/electric/gaulaw.html > > > > > Here comes the fun part. > > > > Do you prepare to learn? Gauss' Law, and indeed many surface integrals, requires definition of a vector dA. It is defined in terms of the normal vector, and the scalar dA. That does not mean that area "has to be a vector". Indeed, as I said the vector area is defined in terms of the scalar area. - Randy
From: Phineas T Puddleduck on 15 Dec 2006 17:14 In article <1166187049.726098.195350(a)j72g2000cwa.googlegroups.com>, "Ka-In Yen" <yenkain(a)yahoo.com.tw> wrote: > Please refer to Gauss's law. > > http://hyperphysics.phy-astr.gsu.edu/hbase/electric/gaulaw.html You'll note it only takes of small areas. -- Just \int_0^\infty du it! -- Posted via a free Usenet account from http://www.teranews.com
From: yen, ka-in on 24 Dec 2006 23:33
Randy Poe wrote: > yen, ka-in wrote: > > In three dimensional vector algebra, area HAS TO be a vector, > > Writing it in caps doesn't make it so. > > Why does area have to be a vector? > > What makes you think scalars can't exist in 3-space? Dear Randy, Thank you for your question. In 3D vector algebra, there are four basic operations: addition, dot product, cross product, and scalar multiplication. To get the area of the parallelogram generated from vectors A and B, cross product has to be used: area=AXB; so the area HAS TO be a vector. |