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Homework Help: Piston & Gas Law Problem

  1. May 16, 2008 #1
    1. The problem statement, all variables and given/known data
    The closed cylinder in the figure has a tight-fitting but frictionless piston of mass M. The piston is in equilibrium when the left chamber has pressure p0 and length L0 while the spring on the right is compressed by delta L. The spring constant of the spring is k.

    a)What is delta L in terms of p0, L0, A, M, and k?

    b) Find an expression for the net force on the piston. Assume all motions of are slow enough for the gas to remain at the same temp.

    2. Relevant equations

    3. The attempt at a solution

    a) I didn't include all of the variables, so it seems that this part is too simple. Here's what I did: F=pA

    so the force of the gas on the piston = the force of the spring on the piston

    deltaL= p0A/k

    b) p1v1=p2v2

    p0(L0)(A) = p1(L0+x)(A)

    p1= p0L0/(L0 + x)

    So the force is pA = Ap0L0/(L0+x) is this right?
  2. jcsd
  3. May 16, 2008 #2
    apistonpressure.jpg here's the figure
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