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Find pressure at depth of freshwater

  1. Dec 4, 2011 #1
    1. The problem statement, all variables and given/known data

    You are scuba diving to reach a ship sunk at a depth of 100m. What is the pressure in atm at this depth? Density of fresh water is 1000kg/m^3 and air pressure at lake surface=1atm=1.013x10^5 N/m^2

    2. Relevant equations

    P2=P1+pgd
    p=density

    3. The attempt at a solution
    P2=P1+pgd
    P2=(1.013x10^5 N/m^2) + (1000kg/m^3)(9.8m/s^2)(100m)
    P2=1081300
    Its at this point that i get confused. I don't know what the units are for this answer.
     
  2. jcsd
  3. Dec 4, 2011 #2
    You have the correct answer for the pressure in N/m^2
    If you are asked for the pressure in atmospheres then you must divide by atmospheric pressure in N/m^2
     
  4. Dec 3, 2012 #3
    instead of 9.8 m/s^2 you should use 9.8 N/kg to get correct units

    (kg/m^3)(N/kg)(m) will give you N/m^2
     
  5. Dec 3, 2012 #4
    Both terms in the equation have to have the same units. That is, the units of the two terms must be consistent. You already know the units of the first term. Just make sure that the units of the second term are consistent. It, of course, helps to know that Newtons are the same kg-m/sec2.
     
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