1. Not finding help here? Sign up for a free 30min 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!

Find the Mass of Air in the Room and the Air's Weight

  1. Jan 27, 2013 #1
    1. The problem statement, all variables and given/known data

    The air in a room measuring 8 ft x 9 ft x 12 ft is at 80°F and 1 atm. Determine the mass of the air, in lb, and its weight, in lbf, if g = 32.0 ft/s2

    2. Relevant equations
    1 °F = 460.86°R

    dair = mair/vair


    3. The attempt at a solution

    The air has the same mass as the room, thus mair = 8x9x12

    mair = 864 ft3

    dair = mair/vair

    dair = ρ/RT

    dair = 1 atm/(53.35 ft lb/lbm °R)(540.67°R)

    dair = 3.4668x10-5 atm lbm/ft lbf

    My density seems kinda low. What am I missing? Is it the gc?
     
  2. jcsd
  3. Jan 27, 2013 #2

    SteamKing

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    You should check your units, especially for R.

    A density unit of atm lbm/ ft-lbf makes no sense.
     
  4. Jan 28, 2013 #3
    Wrong question.
     
    Last edited: Jan 28, 2013
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Find the Mass of Air in the Room and the Air's Weight
  1. Find the air pressure (Replies: 3)

Loading...