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Homework Help: Pressure on a Piston

  1. Sep 4, 2011 #1
    So here's an image of a piston. First of all, this is for a thermodynamics class. Is thermodynamics considered to be "physics?" Do physics majors take thermodynamics?

    So my question is: When writing the forces on the piston, it is obvious that we have the pressures acting on the piston from the gases in the chambers, and also a spring force on the second piston figure. I thought it was also obvious that there is Fg = mg acting on the piston as well. However, when I peeked at the solution manual, weight is not included in the force equation. Why is this?
  2. jcsd
  3. Sep 4, 2011 #2


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    Homework Helper

    Post the exact text of the problem.
  4. Sep 5, 2011 #3
    The piston diameters in Figure are D1 = 10 cm and D2 = 4 cm. When the pressure in chamber 2 is 2000 kPa and the pressure in chamber 3 is 700 kPa, what is the pressure in chamber 1, in kPa?
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