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How do i make a heavy object float?

  1. May 22, 2012 #1
    I have a 5kg gel cell battery that i have calculated to have a buoyancy force of 36.739N and weight of 50N. I need a synthethic foam float to make it float in the water. How do i calculate to make it float?
  2. jcsd
  3. May 22, 2012 #2


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    The density for the battery+float must be less than the density of water. First you need to know the volume of your battery. Then, if you know the density of the foam you are going to use for buoyancy, you can calculate the total volume of battery+foam you will need for it to have a lower density than water.
  4. May 22, 2012 #3
    The foam will give you about 60 lbs of buoyancy per cubic foot. Perhaps a little less depending on which foam you select. I assume salt water. A little less in fresh water.
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