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Thread: Uprooting a tree using a 45:1 pulley system - video

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    Content Editor Altair's Avatar
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    Radioman's Avatar
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    Hmmmm?
    Remembering my high school physics class I believe you add your compound systems not multiply. I think your system is about 10 or 11 to 1 and not 45 to 1. What was your input pull? Let’s just guess 100lbs. In a 10-1 system you’d be pulling at about 1000lbs and not 4500lbs as first stated judging by the way the tree came out of the ground my guess is you were pulling at the lower number? IMHO. it’s been a long time since high school physics class.

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    I'm fairly certain it's a 35:1 system, assuming he actually has a 5:1 at the end. Let's say he pulls with 1lb, that's 5lb out the purple pulley. The line out the purple pulley terminates at the tree, still tensioned at 5lb. That line also runs through that middle pulley, causing the line out to be 10lb. That runs through a red pulley at the tree pulling the tree with 20lb. That runs back and terminates at the tree again, with 10lb of tension.

    So just the tension at the tree: 5+10+20=35lb from 1lb initial force.

    I tried drawing up a diagram, but a nice way to represent it in 2d eludes me lol.

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    Kinda reinforces the perception of the power of the wind in a blow down.


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