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Homework Help: Minimum energy a proton must have to penetrate

  1. Sep 12, 2010 #1
    Minimum energy a proton must have to penetrate....

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

    Determine the minimum energy that a proton must have to penetrate 30 cm of tissue, the approximate thickness of the human body.

    2. Relevant equations
    I used R=[(E/9.29)^1.8]1.11x10^-3 but I'm not sure if this is correct.

    3. The attempt at a solution

    30 cm=3 mm

    3mm=[(E/9.29)^1.8]1.11x10^-3, then I divided by 1.11x10^-3 to get 27027.70mm=(E/9.29)^1.8
    Then I took a root to the 1.8 power and got 80.64mm=E/9.29
    I then multiplied by 9.29 to get 749 mEV.

    Seems a bit high. Wasn't sure about units or if I even used the correct formula?
    Thanks for your help!
  2. jcsd
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