1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Deflating tire, thermodynamics problem

  1. May 10, 2010 #1
    1. The problem statement, all variables and given/known data
    Find the size of the hole in the tire after it has taken 60minutes to become flat.

    2. Relevant equations
    Impulse = F*Deltat = DeltaN*Deltap (N=molecules, p=momentum) , P = F/A (A is area of hole), Equipartition for gas in 1-d -> 1/2kT = 1/2mv^2
    Derivative of ideal gas law (assuming T and V are constant) = dPV=dNkT

    3. The attempt at a solution
    the general equation i came up with that describes the decrease in pressure as a function of time is P = e^-((Aroot(kT)/(2Vroot(m)) *t) + P(initial)) actually ill upload a typed image

    Using a known volume of a tire i am trying to find the initial pressure but im having trouble figuring out how to do it any help would be appreciated. Also im not sure if i have made a mistake in deriving this equation

    Ummm have i explained well enough? Is there more i need to include? Or is the answer not simple? Im sort of waiting for an update if someone could clarify it would be nice.
    Last edited: May 10, 2010
  2. jcsd
  3. May 10, 2010 #2
    Oh i see where i made the mistake. After the integration there should be 1 constant on each side to be combined into another constant which is not P(initial). What a silly mistake. From there it is pretty straightforward.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Deflating tire, thermodynamics problem
  1. Thermodynamics problem (Replies: 3)

  2. Thermodynamics Problem (Replies: 5)

  3. Thermodynamics problem (Replies: 1)