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: Annoying pressure prob. that is so easy i should not have to ask for help

  1. Apr 6, 2007 #1
    A child's helium-filled balloon escapes at sea level and 20.0°C. When it reaches an altitude of 2530 m where the temperature is 5.60°C and the pressure only 0.710 atm, what is the ratio its volume compare to that at sea level?

    so i am going to use the ideal gas law... that is (p1v1)/t1=(p2v2)/t2

    so if the gas is contained in a balloon, that means that the gas will still have the same amount of volume that it could fill so i am going to mulitiply v1 and v2 out so that i have


    p1/293.15 K=0.710/ 278.75 K

    p1=0.74667 atm

    and now for the ratio...i am not sure if it is p1/p2 or p2/p1....but i think it may be p1/p2 and i get 1.05

    either way i do the raito i still get the worng answer...please help me
  2. jcsd
  3. Apr 6, 2007 #2


    User Avatar
    Science Advisor
    Homework Helper

    If you are going to assume that the volume is unchanged, then there is not much point in computing a ratio of volumes, is there? Don't assume that and solve for v2/v1.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook