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Phy properties of matter

  1. Aug 12, 2017 #1
    1. The problem statement, all variables and given/known data
    A 125g pear is immersed at the bottoming of a beaker of water which is filled with 500cm3 of water. Salt of mass 30g was then completely dissolved in the water before the pear begins to float (assume no change In Volume of the water ) given the density of pure water is 1 g /cm2
    1. What is the density of the pear
    2.claculate the buoyant force Acting on the pear before Saltwas added
    3. Initially , what was the apparent weight of the pear in the bottom of the beaker?
    4.how mush of the pear would float above the water if 100g of salt was dissolved in the water instead?

    2. Relevant equations
    Density=mass/volume
    Buoyant force pvg
    Apparent weight = true weight - buoyant force

    3. The attempt at a solution
    I can't find the volume of the pear
     
  2. jcsd
  3. Aug 13, 2017 #2

    PeterDonis

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    Staff: Mentor

    You need to make some attempt at a solution. Note that you are not being asked for the volume of the pear; so one place to start would be to explain why you think you need to calculate the volume of the pear to get the answer being asked for.
     
  4. Aug 13, 2017 #3
    Don't really get it
    I just figured out that the density of the pear will be between 1 to 1.06 as the 1.06 is the density of water plus salt
    The buoyant force is 1.225N
    So the volume of the pear has to divide by the density of pure water or density of water with salt?
     
    Last edited: Aug 13, 2017
  5. Aug 13, 2017 #4

    PeterDonis

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    Will it be "between" those two densities? The problem statement says that the pear is just starting to float when the density of water plus salt is 1.06 (500g of water + 30g of salt in 500 cm^3). What does that tell you?

    You don't need to know the volume of the pear to answer any of the questions.
     
  6. Aug 13, 2017 #5

    PeterDonis

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    Staff: Mentor

    This isn't very clear. What do the symbols mean?
     
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