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Homework Help: Help me with Pressure!

  1. Nov 26, 2007 #1
    1. A bubble of air of volume v forms at the bottom of a container of fluid (neglect effects of viscosity). Let H be the height of the fluid, and let ρf and ρa denote densities of fluid
    and air respectively. How fast is the bubble moving when it reaches the surface?

    2. What is the work performed by the buoyant force on the bubble from the moment it
    forms on the bottom until it reaches surface?

    2. v=vo+at, F=ma, Fb=pvg

    3. I have no clue how to solve this. Im assuming it has to do with the equation P(h)= P(O) +pgH and maybe kinematics? For part b i used Fb=pv(of air)g and multiplied it times H so work=pvgH Thanks
    Last edited: Nov 26, 2007
  2. jcsd
  3. Nov 26, 2007 #2


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    Buoyant force = pf*v*g
    Work done by the buoyant force = pf*v*g*H. According to the conservation of energy this work done must be equal to the KE of the bubble. Maas of the bubble = pa*v. Now you can find the velocity of the bubble.
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