Comments on: With a lever, I move the Earth http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/ Blogging one sidereal day at a time Mon, 15 Mar 2010 20:40:07 -0400 http://wordpress.org/?v=2.8.6 hourly 1 By: Mark Bellis http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-25010 Mark Bellis Mon, 14 Jul 2008 16:59:16 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-25010 The (relatively) easy way to do it would be to build a catapult that would launch mass from the earth's surface at escape velocity - it would have to be a human powered trebuchet if you wanted to narrowly interpret the fulcrum, lever and Archimedes prerequisite. However, this would raise the question if the mass launched from the earth is still considered part of the earth, and so the centre of mass remains the same, did the earth move? (A question that has been asked more than once, but not in this context.) A more elegant solution would be for Archimedes to stand outside during a meteor shower and bat away incoming bolides. This shows that Archimedes anticipated the supposed work of Abner Doubleday by more than 2000 years. Syracuse has always been a great baseball town. The (relatively) easy way to do it would be to build a catapult that would launch mass from the earth’s surface at escape velocity – it would have to be a human powered trebuchet if you wanted to narrowly interpret the fulcrum, lever and Archimedes prerequisite.
However, this would raise the question if the mass launched from the earth is still considered part of the earth, and so the centre of mass remains the same, did the earth move? (A question that has been asked more than once, but not in this context.)
A more elegant solution would be for Archimedes to stand outside during a meteor shower and bat away incoming bolides.
This shows that Archimedes anticipated the supposed work of Abner Doubleday by more than 2000 years. Syracuse has always been a great baseball town.

]]> By: Zeta Connection » Blog Archive » Five Questions with Astronomer Dr. Pamela Gay http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23396 Zeta Connection » Blog Archive » Five Questions with Astronomer Dr. Pamela Gay Mon, 25 Feb 2008 03:44:50 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23396 [...] asked simply: How long would Aristotle’s lever have to be to allow him to move the Earth. I answered that question on my blog, [...] [...] asked simply: How long would Aristotle’s lever have to be to allow him to move the Earth. I answered that question on my blog, [...]

]]> By: Doc Kinne http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23340 Doc Kinne Tue, 19 Feb 2008 14:28:51 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23340 The Thriller Lizard commercial!! The only commercial I remember from the Superbowl this year! :-D Ah. Ummm. Wait. Right. Back to science! The Thriller Lizard commercial!! The only commercial I remember from the Superbowl this year! :-D

Ah. Ummm. Wait. Right. Back to science!

]]> By: blue collar scientist » Blog Archive » Pamela Gay: Best Geek Evah! http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23339 blue collar scientist » Blog Archive » Pamela Gay: Best Geek Evah! Tue, 19 Feb 2008 10:55:02 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23339 [...] Gay, the author of Star Stryder, works out just how big a lever you’d actually need to move the Earth. The starting assumptions are laid out and all the math is laid out in plain [...] [...] Gay, the author of Star Stryder, works out just how big a lever you’d actually need to move the Earth. The starting assumptions are laid out and all the math is laid out in plain [...]

]]> By: George http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23333 George Tue, 19 Feb 2008 02:21:08 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23333 Wow, and that's only at 5km. The Earth isn't all that moveable, afterall. :) The coefficient of friction at the fulcrum, along with a few other things, might be a slight problem. :) It is still a very cool result. Wow, and that’s only at 5km. The Earth isn’t all that moveable, afterall. :)

The coefficient of friction at the fulcrum, along with a few other things, might be a slight problem. :)

It is still a very cool result.

]]> By: Freiddie http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23330 Freiddie Mon, 18 Feb 2008 23:46:27 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23330 I never would have thought that it's that tough! I never would have thought that it’s that tough!

]]> By: pamela http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23325 pamela Mon, 18 Feb 2008 15:35:00 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23325 Hi Farstarz- If Earth sits all by its lonesome in the middle of nothing, it will experience no forces. If you then drop in a second planet, the Earth will experience a gravitational force toward the second planet, and that force is defined by F=GMm/r^2. The second planet will also experience an identical force in the opposite direction. Each of these forces will generate an acceleration that you can solve for by setting the force above equal to F=ma, and solving for 'a'. Now, if I want to move the Earth, my force has to be great enough to overcome the other planets force, and great enough to move the Earth (overcome its desire not to move). This is roughly the difference between exerting the amount of force on a cat on tile needed to cause it to run in place while trying to escape, and exerting enough force to get it to slide backwards while it tries to run forward. And Stuart - Thanks! Hi Farstarz- If Earth sits all by its lonesome in the middle of nothing, it will experience no forces. If you then drop in a second planet, the Earth will experience a gravitational force toward the second planet, and that force is defined by F=GMm/r^2. The second planet will also experience an identical force in the opposite direction. Each of these forces will generate an acceleration that you can solve for by setting the force above equal to F=ma, and solving for ‘a’. Now, if I want to move the Earth, my force has to be great enough to overcome the other planets force, and great enough to move the Earth (overcome its desire not to move). This is roughly the difference between exerting the amount of force on a cat on tile needed to cause it to run in place while trying to escape, and exerting enough force to get it to slide backwards while it tries to run forward.

And Stuart – Thanks!

]]> By: farstarz http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23324 farstarz Mon, 18 Feb 2008 14:31:35 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23324 Why not simply F = ma ? "..have to over come not only the "inertia" of the Earth, but also the "force that other planet" is exerting on it.." => aren't they the same? Why not simply F = ma ?

“..have to over come not only the “inertia” of the Earth, but also the “force that other planet” is exerting on it..” => aren’t they the same?

]]> By: Stuart http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/comment-page-1/#comment-23323 Stuart Mon, 18 Feb 2008 12:20:14 +0000 http://www.starstryder.com/2008/02/18/with-a-lever-i-move-the-earth/#comment-23323 Pamela, reading your post made me think of <a href="http://xkcd.com/356/" rel="nofollow">this xkcd comic</a> - in a good way ;-) Pamela, reading your post made me think of this xkcd comic – in a good way ;-)

]]>