----- Original Message ----- > From: "mix...@bigpond.com" <mix...@bigpond.com> > To: "vortex-l@eskimo.com" <vortex-l@eskimo.com> > Cc: > Sent: Saturday, August 6, 2011 6:19:54 PM > Subject: Re: [Vo]:Revisiting The "Whipmag" All-Magnet Motor, saga > > In reply to Harry Veeder's message of Mon, 1 Aug 2011 19:22:34 -0700 (PDT): > Hi, > [snip] >> This reminds me of a pre 17th century argument that the Earth cannot be > turning. >> As everyone knows if the Earth was turning then the ground would move away > from you whenever you jumped in the air. However from our experience we know > it does not, theorefore the Earth is not turning. > > Actually the old argument is correct, in concept, but wrong in magnitude. > In order to come down in exactly the same spot (assuming a perfectly vertical > jump), one would have to maintain the same angular velocity (degrees of arc / > second) in the air that one had on the ground (and, due to the larger radius, > travel a larger distance at a higher linear velocity parallel to the surface). > Since one's linear velocity is not going to increase (conservation laws), > one > always comes down a tiny distance West of where one started. > Regards, >
According to the old the argument if you were jumping at the equator and stayed in the air for a second in that time the ground would be expected to move about 1500 hundred feet. If you are wondering why people thought like this, it is because in aristotelian physics lateral motion could not happen without an applied force, whereas downward or falling motion was considered natural or unforced. It was thought a thrown stone would continue to move laterally because the air would continually rush in behind it and keep pushing it forward. Harry
