Centripetal anomalies

[nick hall]

AlanR wrote:

"The moving mass (the luge) has a kinetic energy determined by Gravity and the vertical drop "

Actually, in the example you quote, this isn't so. The downward force acting on the luge is indeed gravity. BUT against this is a small upward component derived from the centripetal force - or rather the centrifugal force (speaking from the luge's perspective!)

In other words, assume your vertical drop was 1 metre, you can't simply compute the kinetic energy using gravity alone over that distance - it has to be gravity MINUS the small upward component.

Yes, going down a vortex increases 'the time the luge is exposed to gravity' but not JUST gravity but gravity-minus-a-small-upward-component. I think you'll find no net gain...

In practice of course, your vortex offers much more potential for drag (friction) than a straight vertical drop through air!

Put it another way, after falling vertically one metre or after falling a vertical height of 1 metre down your vortex, the resultant KE would be the same (assuming no losses).


Thanks

Nick

[Jonathan]

I have already made this point myself, in the correct thread, that we have not yet proved that the equations don't cancel out. If you know something, show me, if you don't, and you really did mean:

I thinkyou'll find no net gain...

then be quiet, because I have already made this point.

[ovyyus]

Jonathan,

Perhaps everyone should just be quiet and listen to you? School's in :)

Cencorship is the primitive response of intolerance.

[Jonathan]

That doesn't make any sense, I'm telling him to be quiet because that point has already been made, and is obvious, and yet he tells me it like I'm an idiot. If I have in any way cencored him, I have cencored myself, because I already said that.

[AlanR]

Nick

you can't simply compute the kinetic energy using gravity alone over that distance - it has to be gravity MINUS the small upward component.

OK - but what if we force the ball UP the spiral, ie on the "upgoing" side of a gravity wheel we force the ball to travel a spiral. (how?) Wouldn't Fc still have the "small upward component" which would essentially reduce the balls apparent weight? If that were true then it would take less energy to raise the ball to the top of the wheel than that gained on the downward (power) section. Voila assymetry. I make it sound too easy ;-)
(Sure the reaction to the small, upward force is a small, downward force upon the ramp itself, so the ramp would not be part of the moveable structure)

Regards, Alan

[Jonathan]

Now that seems to be a good point, though seemingly impractical as I can't think of anything off the top of my head that would fit that unusual discription...I wish this is all I had to do all day, I hate not getting to work on this, I love these impossible puzzles.