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Why is strain greater in longer wires?

  1. Jan 4, 2012 #1
    I'm doing A-Level physics and I've been answering questions on Young's Modulus. I need to be able to explain why a long, thin wire is used when measuring the Young's Modulus of a material. I can give an explanation of why stress due to the wire being thinner is greater but I don't know why stress is greater in a thinner wire. Any help in understanding this would be much appreciated.

    Thanks for taking your time to read this.
     
  2. jcsd
  3. Jan 4, 2012 #2
    First take a look at the heading for your question in the light of your definition for strain.

    What is your definition for strain?

    Then look at your definition for stress.

    Hint
    Stress and strain are both relative to (depend on) the dimensions of the body concerned.

    Force and extension are not.
     
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