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Homework Help: Kinetic energy to PSI

  1. Jul 19, 2011 #1
    1. The problem statement, all variables and given/known data

    What is the resulting PSI when the kinetic energy of 100 kg at 7 m/s is used to compress air into a 15cm x 15cm x 60cm tank?

    2. Relevant equations

    Kinetic energy K = 0.5mv^2
    Boyle's Law PV = K

    3. The attempt at a solution

    .5 x 100 x 7^2
    50 x 49 = 2450 joules

    .15 x .15 x .6 = .0135m^3
    .0135 x V = 2450
    V = 181481 pascals
    V = 26.3 psi

    ** is this correct? seems like the psi is too small
  2. jcsd
  3. Jul 20, 2011 #2
    You can't just sanity check the pressure;

    What if the tank were the size of a football stadium? Then 28 PSI would be a huge pressure for this problem.

    It seems right to me for the size of the tank.
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