Search All of the Math Forum:
Views expressed in these public forums are not endorsed by
Drexel University or The Math Forum.



Re: The rotating spaceship. Is the centrifugal force a real force?
Posted:
Jan 22, 2013 3:07 AM


On Jan 18, 9:27 am, Tom Roberts <tjroberts...@sbcglobal.net> wrote:
> "Centrifugal force" is always fictitious, and is not real in that it is not a > model of any physical phenomenon.
Nonsense, the centrifugal force is very real to someone who experiences it. As a professional experimental physicist, you should have no problems in devising an experiment to show how real this force is to the occupants that experience this force. So, it depends on which frame of reference you are looking at. <shrug>
> "Centrifugal force" is always an artifact of using rotating coordinates; it > never appears when using an inertial frame.
Please stop making socalled inertial frames of reference the holy frames of reference. All frames of references are the same. The laws of physics are the same from one frame to another whether it is a holy one like the inertial or a rotating one. It is totally surprising that Tom has so much trouble in understanding this. <shrug>
> As nature never uses coordinates, > any coordinatedependent quantity is necessarily a human artifact of the > analysis, and cannot be present in the physical system.
So, you always need the coordinate system to describe what you are observing without any exceptions. What you are saying is just total nonsense then. In fact what you are doing is to build up excuses to handwave mundane phenomena away as myths. <shrug>
> Whenever your body is subject to a real force, you can feel it (ignoring forces > too small to be felt, or so large they kill you). This is because your body > senses the distortion of your tissues due to different forces acting on > different parts of your body; "centrifugal force" acts identically on all parts > of your body. When your car takes a tight corner, you do not feel any > "centrifugal force", you feel the force from your seat, seat belt, and perhaps > the car's door  they are all pushing INWARD (i.e. they are centripetal > forces), and cannot possibly be the outward "centrifugal force".
See! It did not take Tom too long to devise experiments to show how real the centrifugal force is. <shrug>
> Similarly, "gravitational force" is not real,
Here we go. More bullshit is coming to our town. <shrug>
> in that it is not a model of any > physical phenomenon, and it cannot be felt.
Tom, you are totally bullshitting. Koobee Wublee sitting on His chair is feeling gravity right now as He types away. <shrug>
> You clearly feel the force of a > chair pushing up on your backside, or of the floor pushing up on the soles of > your feet;
Yes, it must be very real. Koobee Wublee can assure Tom that Koobee Wublee has not been using any hallucinogens. Yes, Koobee Wublee is feeling gravity, and gravity is certainly very fvcking real to Koobee Wublee. Holy cow! Gravity is just so fvcking real! <shrug>
> skydivers feel the force of the air pushing up on their bodies and > parachutes. In low earth orbit, the earth's 1/r^2 "gravitational force" is only > a few percent less than on the surface, but astronauts in the space station > clearly do not feel it; people on the surface don't feel it either, but may > confuse it with the upward force on their feet.
Hello, Tom! Have you seen the geodesic equation that has the centripetal force canceling out the centrifugal force? If not, Koobee Wublee suggests Tom to study harder, and only by studying will Tom ever to push mysticism out of his mind. <shrug>
> In GR, Einstein got it right  these fictitious "forces" are not real, they are > merely coordinatedependent artifacts of the geometry.
Koobee Wublee does not know how Tim interprets his GR, but according to the geodesic equations under the more general differential geometry, gravity certainly cancels out centrifugal motion in a circular orbit. Not to say GR is valid in general, but everything GR predicts just agrees with everything Newtonian results to the first order. In differential geometry and from the field equations, it can easily be interpreted as gravity being a force manifested from gravitational time dilation instead of worshipping the curvature of spacetime. <shrug>
So, is it a matter of whose interpretation to GR is superior? No, the mathematics will decide that. Want to go there, Tom? Koobee Wublee knows Tom cannot. Is there someone else who would like to show gravity is merely a fictitious artifact in the curvature of spacetime? <shrug>
The following equation is derived from Larmor?s transform showing how real force is. See how simple and elegant it is. <shrug>
** (P^2 ? F^2 c^2) / (1 ? B^2) = Invariant
Where
** P = Observed power ** F = Observed force ** B c = Observer?s absolute speed
You might be able to find one to satisfy the principle of relativity, but good luck with that. <shrug>



