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Homework Help: Greatest elongation and escape velocity HELP

  1. Jun 8, 2010 #1
    1. The problem statement, all variables and given/known data

    Three wires are made of same materials. Which wire will have the greatest elongation?
    wire1: length: 50cm, diameter: 0.5mm
    wire2: length: 100cm, diameter: 1mm
    wire3: length: 300cm, diameter: 3mm
    2. Relevant equations



    3. The attempt at a solution

    I know, the wire having greatest elongation will have the greatest Young's modulus.
    So, i have to calculate the young modulus from the given data of the three wires. but I cant get a equation to put.
    actually i'm weak at the elasticity related issues, but I guess It's not too hard....


    1. The problem statement, all variables and given/known data

    The escape velocity from earth is v. if the body is projected from the earth in a direction of 45 degree to the vertical then it's escape velocity is??


    2. Relevant equations



    3. The attempt at a solution

    I think, the escape velocity will not change...it's same for all direction....am I wrong?
     
  2. jcsd
  3. Jun 8, 2010 #2

    PhanthomJay

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    Science Advisor
    Homework Helper
    Gold Member

    I would like to welcome you to these forums and would ask that you post separate unrelated questions in separate posts, and to please show an attempt at your work when posting, listing relevant equations.
    this is not true
    It is given that all wires have the same material, therefore, they all have the same Young modulus, which is a property of the material structure.
    You'll need to list the relevant equation that relates elongation to Young's modulus and the given variables.
    You may very well be right, with the usual assumptions of no air resistance, etc., but why do you say that?
     
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