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Subject: 
Re: A space physics question
Newsgroups: 
lugnet.off-topic.geek, lugnet.space
Date: 
Sun, 29 Dec 2002 12:16:24 GMT
Viewed: 
731 times
  
In lugnet.off-topic.geek, Jon Palmer writes:
Imagine a winch pulling a rope or cable through a series of pulleys
(horizontal) that are staked to the ground. The pulleys are arranged so that
the rope makes a zig zag pattern on the ground.  There is an object at one
end of the cable, being reeled in by the winch at the other end (ignore for
now that the object would collide with the pulleys)

The pulleys and winch stay in place because they are anchored to the ground.

Now imagine this setup on a much larger scale in space.  The pulleys and
Winch, no longer tethered to anything, would not be able to stay in the same
spot.

But what if the winch and pulleys had thrusters on them to maintain their
position?  Is that possible?

Start with the winch.  It's reeling in the object at the other end of the
cable.  In my mind the winch would also reel it's self in, so that it and
the object would meet in the middle.  If it had thrusters, in this case
aimed towards the object, could it maintain it's position if it supplied
thrust which was equal in energy to the pulling of the cable?  Disregard
fuel use etc.. Imagine that the thrusters could maintain a constant rate
throughout the reeling process.

So now think about the smaller pulleys that are spaced out along the cable.
In order for them to maintain the precise zig zag pattern (this is crucial)
they would need thrusters too.  I imagine if they didn't have them the winch
and object would eventually pull the length of the cable straight.

Imagine for a moment that this is possible.  The small pulleys would
disengage and shoot away (or explode perhaps) from the cable just before the
object hit them.  This would correct the course of the object.  ex: It was
going left, now it's going up and to the right, on its way to the next
pulley.

Thoughts?

[ j o n ]
--
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I think it's all reletive to the 'load' on each end.  I realize there is no
weight in space so we'll talk in inertia or mass.  If you are a single
person winching a large object such as a ship or asteroid or other large
mass... then if we apply Einstein's space-time theory the object with the
larger mass will move less and you will NOT meet in the middle, you may move
the large object but odds are you will just winch yourself in.  The larger
object will have more mass and require a greater force to move it, even in
space.  If both ends have the same mass, then yeah, you said it all.

e.



Message is in Reply To:
  A space physics question
 
Imagine a winch pulling a rope or cable through a series of pulleys (horizontal) that are staked to the ground. The pulleys are arranged so that the rope makes a zig zag pattern on the ground. There is an object at one end of the cable, being reeled (...) (22 years ago, 28-Dec-02, to lugnet.off-topic.geek, lugnet.space)

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