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I Load on a Horizontal Wire (Zip line)

  1. Aug 18, 2015 #1
    I am creating a horizontal zip line, in which a rider will be pulled with a rocket engine. Completely serious. One end of the wire will be secured to a tractor and the other to a large tree.

    The zip line will be made from 12.5 gauge (2 mm) galvanized class 3 200 KPSI minimum tensile strength, high tensile smooth wire. It has a 680 kg (1500 lbs) minimum breaking load. I purchased the wire without the intention for it to support a rider. I would like to use this wire, purchasing a lower gauge (thicker wire) is not possible. Here is a link to the product I have. I attached a image of the product tag as well.

    My question is, at a distance of 1200 ft (366 m), would the wire be able to support the load of a person 91 kg (200 lbs) on a pulley? If one wire length ins't enough, would two wires running parallel, each with separate pulleys (splitting the load: 91 kg / 2) be able to support the load?

    I know so far:
    -With a mass of 91 kg, the weight of the load would be 91 kg * 9.81 m/s (gravity), therefore the load would actually be 893 kg and require 893 kg / 2 = 446 kg at each end of the wire to keep tension on it. Here is a source https://www.physicsforums.com/threads/zip-wire-loading.244497/ and see also https://www.physicsforums.com/threads/calculating-horizontal-wire-cable-load.42371/

    Any help would be greatly appreciated, thanks in advance! This is my first thread on Physics Forums :)


    Attached Files:

  2. jcsd
  3. Aug 18, 2015 #2


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    Staff: Mentor

    Welcome to PF.

    The last post in that thread, before it was locked, says:
    A completely horizontal zip line is completely impossible. The tension will depend on how much sag you are willing to accept and is easily calculated with trigonometry (a horizontal zipline isn't applying any component of force upwards....the angle determines the component of force in each direction). Beyond that, we can't help you with something so inherently dangerous in amateur hands. Please do not attempt this: it is not safe.
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