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Homework Help: Pressure cooker question!

  1. May 10, 2010 #1
    1. The problem statement, all variables and given/known data
    A pressure cooker has a lid screwed on tight. A small opening with A=5 mm2 is covered with a weight which can be lifted to let steam escape. How much mass should the weight have to allow boiling at 120 C with an outside atmosphere at 101.3kPa


    2. Relevant equations

    p=f/a therefore f = pa and the mass will be equal to pa/g

    saturated water pressure at 120C is .2 Mpa
    atmospheric pressure is 101.3 Kpa

    m = (200000-101300)(.005)/9.8 = 50.36g

    3. The attempt at a solution
     
    Last edited: May 10, 2010
  2. jcsd
  3. May 10, 2010 #2
    Right so someone tell me if I'm correct here:

    p=f/a therefore f = pa and the mass will be equal to pa/g

    saturated water pressure at 120C is .2 Mpa
    atmospheric pressure is 101.3 Kpa

    m = (200000-101300)(.005)/9.8 = 50.36g

    Am I correct?
     
  4. May 10, 2010 #3
    correct!
     
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