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Old 12-09-2007, 03:40 AM   #3
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Another thing people ask is, what if I push down the bar to the horizontal position?
I took an quick measurement with my dropweight machine. The radius of the tensioner is about 1.2 inches, and the length of the tension bar is about 19 inches.
If I apply a force of 1 pound at the end of the bar to keep the bar horizontal, I'm over-tensioning the string by nearly 15 pounds!!!

How did I come to this conclusion?

Look back to this equation:
f x r = M x g x R

If I apply 1 pound at the end of the 19-inch bar, I will add an extra torque of 19 pound-inch on the right side (torque). That's the same amount of torque the left side has to come up with. Since the "r" for the left side is only 1.2 inch, the extra "f" it will have to have is about 15 pounds (the ratio of the 2 radii: 19 inch divided by 1.2 inch)!

If you have a stiff poly and you're pushing down by a force of 2 pounds, you're over-tensioning by over 30 pounds! It can easily break!
"Physics is like sex: sure, it may give some practical results, but that's not why we do it." -- Richard P. Feynman

Last edited by lethalfang; 12-09-2007 at 09:25 PM.
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