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!

Homework Help: Determine the diameter of a piston

  1. Nov 19, 2016 #1
    1. The problem statement, all variables and given/known data
    Determine the diameter of a piston if the working stroke of a piston is ##h## and if a working cylinder ##(720^\circ )## describes the following ##p(V)## diagram, where on the ##x## axis is a ratio between the current volume of a piston and the total volume (swept + clearance volume). The compression rate is 7.5:1.

    2. Relevant equations

    3. The attempt at a solution
    I was able to calculate the height of the clearance volume (assuming it has the same shape as swept volume) by the following equation $$\frac{V_{clearance}+V_{swept}}{V_{clearance}}=7.5$$ so $$a=6.5 h.$$ And I honestly tried to calculate the diameter but everything I do leads me only to a ratio of some volumes, ergo the diameter falls out of the equation. I simply don't have an idea how to calculate the diameter of a piston.
  2. jcsd
  3. Nov 20, 2016 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I see your difficulty. It makes no sense to me either.
    Btw, I believe the given h is Vswept, so your a = 6.5h is backwards.
  4. Nov 21, 2016 #3
    I apologize, I misread the problem statement. The swept volume ##V_{swept}## is also given. In that case, this is all a trivial problem.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted