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Homework Help: Will the scuba diver sink or float

  1. Oct 29, 2013 #1
    1. The problem statement, all variables and given/known data
    A scuba diver and her gear displace a volume of 65.0L and have a total mass of 68.0kg. What is the buoyant force on her and will the diver float or sink.

    2. Relevant equations


    3. The attempt at a solution
    The first thing I did was find the weight of the diver as w=mg=68.0kgX9.8m/s2=670N
    Then I tried to find the buoyant force using archemedes' principal (FB=pH20Vg
    I used the given density as 103 kg/m3, the volume of water displaced is 65.0L, which I converted to m3 by using the factor of 103L/1m3 to get 6.5X104m3. The equation then becomes
    and I get 6.4X108N, which is greater than mg, so the diver would float.

    I'm wondering if this is correct or not

    Edit: Forgot to mention, I'm not too concerned with sigfigs, as long as the answer is withing a reasonable variance the teacher will give me credit.
  2. jcsd
  3. Oct 29, 2013 #2
    That buoyant force is awfully large. Check your L to m^3 conversion
  4. Oct 29, 2013 #3


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    Staff: Mentor

    How much does 65L of water weigh?
  5. Oct 29, 2013 #4


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    Staff: Mentor

    Salt water, or fresh water?

    Not that it matters much in this case, but it matters when you dive.
  6. Oct 29, 2013 #5


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    Staff: Mentor

    Good point! :smile:
  7. Oct 29, 2013 #6


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    Staff Emeritus
    Science Advisor
    Homework Helper

    If there are 1000 L in 1 m^3, how can 65 L = 65000 m^3?

    That's the amount of water displaced by a large ship.
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