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!

Question about Atmospheric pressure

  1. Nov 26, 2011 #1
    1. The problem statement, all variables and given/known data
    The problem is this: If T(temperature) AND P(pressure) of air increases, what can we assume about D(density)?


    2. Relevant equations
    Well, I know that as temperature increases, pressure increases and vice versa. When you try this question out with the equation P=KdT it doesn't quite make sense. It all depends on how much the pressure increases and how much the temperature increases, correct? Let's say the pressure goes up from 33 KPa to 101.32 KPa but the temperature only goes from 233 Kelvin to 235 kelvin. Both the P and T increased but the density would increase. However, if the pressure only goes up by, say, 5 mb and the temperature increases from 20 K to 308 K then the density would decrease. If the pressure and temperature increase by the same rate (corresponding to the equation) then the density would remain the same.


    3. The attempt at a solution
    At first i said decrease, but then I assumed that my teacher meant that if P and T increase an equal amount, so I said density would stay the same. What is your guys' opinion on how to answer this? Would you say it depends on how much the T and P goes up or would you say it would remain the same? Or is there a different, correct solution? Thanks everyone. Any input is appreciated
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
    Last edited: Nov 26, 2011
  2. jcsd
  3. Nov 26, 2011 #2
    Why don't we assume ideal gas conditions and start from

    PV=nRT where n is the number of moles

    and try to modify above equation to the form P=KdT?
     
  4. Nov 26, 2011 #3

    Borek

    User Avatar

    Staff: Mentor

    Yes.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook