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Homework Help: Buoyant Force

  1. Nov 22, 2011 #1
    1. The problem statement, all variables and given/known data

    A 5-kg object displaces 10 kg of water. What is the force required to submerge the object?

    a. 24 N

    b. 147 N

    c. 98 N

    *d. 49 N

    2. Relevant equations

    Buoyant Force = Weight of the Water displaced

    3. The attempt at a solution

    Weight of the Water displaced=10kg*9.81m/s^2=98.1N

    If the buoyant force is 98.1N an equal or greater force must be applied to submerge the object.

    The answer key says its 49N...why?
     
  2. jcsd
  3. Nov 22, 2011 #2
    You are forgetting about the weight of the object. If you draw a free body diagram and apply all the forces, it becomes obvious.
     
  4. Nov 22, 2011 #3
    Ohh right the object pushed downward too
     
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