Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Thermodynamics: adiabatic processes

  1. Mar 17, 2009 #1
    1. The problem statement, all variables and given/known data
    A multicylinder engine in an airplane operating at 2500 rev/min takes in energy 7.89 x 10^3 J and exhausts 4.58 x 10^3 J for each revolution of the crankshaft. (a) How many litres of fuel does it consume in 1.00 h of operation if the heat of combustion is 4.02 x 10^7 J/L ? (b) What is the mechanical power output of the engine? Ignore friction and express the answer in horsepower. (c) What is the torque exerted by the crankshaft on the load? (d) What power must the exhaust and cooling system transfer out of the engine?

    2. Relevant equations
    e = Weng / Qh = 1 - Qc/ Qh

    3. The attempt at a solution
    I just have no idea where to start this, so any tips would be greatly appreciated
    Last edited: Mar 17, 2009
  2. jcsd
  3. Mar 17, 2009 #2
    bump for help
  4. Mar 18, 2009 #3


    User Avatar

    Hi, Arin. It's Gareth. :) I was looking for help on the same question, and this was the first page on Google.

    Anyway, if you still want help, I found this other page that has the step-by-step answers: http://www.csupomona.edu/~skboddeker/132/assign/ch22h.htm [Broken]
    Last edited by a moderator: May 4, 2017
  5. Mar 18, 2009 #4
    haha hey, yeah i found another site that had a bit of an explanation to it, but it didn't have c) or d) to it. thanks
  6. Mar 18, 2009 #5


    User Avatar
    Homework Helper

    hi zandbera, welcome to PF
    so where are you at with the problem? helps to show some work so we know where you are getting stuck
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook