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Movable Pulley Help

  • 12-02-2011 9:13pm
    #1
    RHRN
    Closed Accounts Posts: 357 ✭✭


    Hi, I'm a fifth year student self-teaching applied maths, and I was wondering if you could help me.

    I've been doing okay so far, and I'm finding this topic alright except one little thing. They've told me for some questions that http://www.skoool.ie/skoool/examcentre_sc.asp?id=2591 have a system like the third diagram here, that when B descend Y metres, and A ascends x metres, that y=2x. But, they're asking me why.

    Wondering if I could get some help, or even a push in the right direction would be greatly apreciated!


Comments

  • #2
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    If A ascends x metres, the two sections of rope on either side of A will be shortened by x metres. I.e. A total shortening of 2x. But since the entire length of rope is constant, a total shortening of 2x at A means a lengthening of 2x at B.


  • #3
    RHRN
    Closed Accounts Posts: 357 ✭✭RHRN


    Thanks, it seems so obvious now when you say it :o
    I thought the two pieces of rope had something to do with it, but I was having a blank :o
    Thank you anyway :)


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