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[Towertalk] Statics 101

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Subject: [Towertalk] Statics 101
From: (Tom Rauch)
Date: Fri, 12 Jul 2002 03:06:40 -0400
> Statics 101: An object is at rest when the forces up equal the forces
> down.
> Don't matter how many pulleys you use, unless you make a second
> attachment to the tower you don't gain anything as the ground crew
> holds the rope (same as tieing it to a ground) and the gin pole takes
> out twice the load since there are two equal downward force vectors. 

The downward force on the pole is the SUM of the weight of the load 
and the force needed to "pull" down on the rope to lift the load.

If you have a 100 pound load the compression on an ideal frictionless 
vertical pole would be 200 pounds, because the force pulling on the 
rope would add to the compression load on the pole.

If you used a mechanical advantage *at the pole*, it would reduce the 
pulling force on the rope (but increase distance) so you would have 
load + some lesser force depending on mechanical advantage.

You'd have a minimum pole load of the original load plus whatever tug 
is required on the rope. 

Of course if you added mechanical advantage at the tower base, it 
would do nothing at all for the pole.73, Tom W8JI 

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