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Question about Specific Gravity.

  1. Aug 6, 2013 #1
    I know that if the specific gravity is less than 1, it will float and if it is greater than 1 it will sink. Now here's the question, if the specific gravity is equal to 1, what will happen? Please I need your explanations. Thank you so much!
  2. jcsd
  3. Aug 6, 2013 #2


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    The object will stay at whatever depth it's placed - as long as it's totally immersed - because the upthrust is equal to the weight (no net force). If some of it is above the surface, it will sink (and then continue moving downwards until the Kinetic Energy is dispersed due to drag).
  4. Aug 6, 2013 #3


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    So, the specific gravity of a thing is the ratio of the density of that thing over the density of water.

    The buoyant force from water is equal to the weight of the displaced water.
    If the density of your object is the same as the surrounding water, then the buoyant force of the water pushing on the object will cancel with the weight of the object, giving you no net force.

    In this case, (as has been said) the object will stay put wherever underwater you place it.

    However, the density of water is not contant, it changes (very slightly) with temperature and pressure.

    In order to be exactly certain that the net force will be precisely zero, one needs to know the standard temperature and pressure the specific gravity is based on. Wikipedia has an excellent article on the subject.
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