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| Joined: | Thu Mar 26th, 2009 |
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new edit: (and it looks like you got it figured out while I was typing)...I've thought about this a bit myself and looked into it a bit and concluded that an automatic watch WILL IN FACT work in space, even in the presence of zero gravity.
In reading about the manual wind Omega Speedmaster, it appears to me that NASA chose the manual-wind Omega Speedy for use in space based on very specific criteria which included a long list of POSSIBLE severe environments (and I think the Speedmaster was chosen in 1965 and Omega didn't make an automatic version until 1973...for whatever reason, Omega submitted the manual wind version to Nasa for the 1978 selection and it was selected based on the long list of criteria).
Nasa mistakenly believed that gravity was required to spin the rotor of an automatic watch, however, which was an incorrect assumption. In reality, INERTIA moves the rotor of an automatic, not gravity (The principle of inertia can be stated as - "In an isolated system, a body at rest will remain at rest and a body moving with constant velocity will continue to do so, unless disturbed by an unbalanced force"). In the case of automatic watch, the unbalanced force is the rotor.
I think of it this way...An automatic watch winds through the use of a weighted rotor attached to the watch movement. As the watch moves (from the movement of the person's arm, for instance), the rotor does not want to move, however, because its center of mass (the rotor) is different that the center of effort (the rotor shaft), the rotor begins to spin. And as the rotor spins, it winds the watch.
Now there are some things that are correct when thinking about gravity and winding an automatic movement...It's correct that in a gravity field, you can keep a watch stationary and rotate it, which makes the rotor turn and wind the watch. Like for instance in a watch winder, which definitely WOULD NOT wind a watch in zero gravity. BUT that's not the only way you can get the rotor to turn...Imagine placing the watch flat on a table and pushing it back and forth. Of course the rotor would turn, but you haven't involved gravity in the least...you are using Inertia.
OK...this has become way too geeky of a discussion...but that's how I see it.
Last edited on Mon Sep 6th, 2010 01:28 pm by stew77