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Upthrust in a fully submerged object

  1. Oct 27, 2011 #1
    When we put any object in a fluid it experiences upthrust. Suppose an iron cube is put in a beaker with water. It sinks and reaches bottom. When it reaches bottom and touches the base of beaker there is no water below it. Then will it experience upthrust?
  2. jcsd
  3. Oct 27, 2011 #2
    The block experiences a buoyant force equal to the weight of the volume of water displaced...After it sinks to the bottom,because the weight imparted by gravity exceeds the buoyant force, the beaker then exerts an additional force sufficient to keep the block in equilibrium....
  4. Oct 27, 2011 #3
    There is no water below cube. So pressure is exerted on all sides except bottom.
    Is my assertion right?
  5. Oct 27, 2011 #4
    If the cube is stationary, its bottom will experience a force equal to the weight of the cube plus the weight of the water in the column above the cube. (Plus the weight of the air in that column extended to the edge of the atmosphere, if we want to be persnickity.) If there is truly no water beneath the cube, that force will be exerted by the bottom of the beaker. If there is some water beneath the cube, the force will be distributed between the beaker and the water.
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