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Pressure of Crutches

  1. May 2, 2012 #1
    1. The problem statement, all variables and given/known data

    A 72 kg person sits on a 4.0 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.1 cm in diameter. Find the pressure exerted on the floor by each leg of the chair, assuming the weight is equally distributed.

    2. Relevant equations

    P=F/A
    A=∏r^2

    3. The attempt at a solution

    To find the force, I added the mass of the person and the mass of the chair and got m=76kg. Then i multiplied that by g=9.81 and got F=745.56.
    To find the area, I converted 1.1 cm into meters, .011, and found the area A=9.5*10^-5
    then i divided F/A and got P=7845260 but this is incorrect.
     
  2. jcsd
  3. May 2, 2012 #2

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    Okay, that's good.

    Did you recall that the chair has four legs? Oh, and be sure to include units of measurement.
     
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