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Homework Help: Acceleration of a Hot Air Balloon

  1. Nov 9, 2009 #1
    1. The problem statement, all variables and given/known data
    What is the magnitude of the acceleration of a rising hot-air balloon if the ratio of the air density outside the balloon to that inside is 1.25? Neglect the mass of the balloon fabric, the basket and it contents.

    I don't know how to do a rho so "p" will be rho for density and P will be for pressure
    o = outside of balloon
    i=inside of balloon

    po = 1.25pi
    po (of air) = 1.2 kg/m^3
    Po = 1atm = 101.3 kPa

    2. Relevant equations

    P+1/2pv^2+pgy = P+1/2pv^2+pgy
    p = m/v

    3. The attempt at a solution

    I'm really stuck at the beginning of this problem. I can't seem to find any way to link density and acceleration (without time and a distance or and area). Any suggestions? Also are my assumptions about Po and po right? Seeing at I'm unsure of the elevation/air temp I can't be sure. Also are there other assumptions I should be making? Thanks!
    Last edited: Nov 9, 2009
  2. jcsd
  3. Nov 10, 2009 #2
    actually it is easier to draw the force diagram first :)
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