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Homework Help: What is the density of the stone?

  1. Aug 12, 2009 #1
    1. The problem statement, all variables and given/known data

    When a 50 N stone is attached to a spring scale and is
    submerged in water, the spring scale reads 35 N. What is the density
    of the stone?

    2. Relevant equations

    3. The attempt at a solution
    I found that the buoyant force is 15 N but i dont know what to do after. Can someone please help me step by step. I need to know this for my final tomm and im stressing out.
  2. jcsd
  3. Aug 12, 2009 #2
    Re: Buoyancy

    i know it becomes 1000(50)/ 15 but i dont know where the 1000 came from. can someone please help?
  4. Aug 13, 2009 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Re: Buoyancy

    Now you know the buoyant force you also know the volume of the boulder is the same as the volume of displaced water. So you can work out its volume in terms of the density of the water. Next you just divide its mass by the volume to find its density.
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