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Fluid Problem

  1. Jun 1, 2005 #1
    hi guys

    if you have an aluminium sphere of volume 0.006 metres cubed, how do you find the gravitational force acting on the sphere, as well as its acceleration (ignoring water resistance)

    Also, if your given the area and velocity of a fluid at two points of hose, how can you find the pressure at these two points in the hose?
  2. jcsd
  3. Jun 1, 2005 #2


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    What does water resistance have to do with gravitational force? You need to state the entire problem and maybe we can help. The force due to gravity is simply the sphere's weight.

    You are going to have to know one of the pressures to calculate the other, or you could calculate the delta P between the two points, but that won't tell you anything about the individual pressures. For simplicity, use the Bernoulli equation.
  4. Jun 1, 2005 #3

    Chi Meson

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    You probably have a table that lists the density for aluminum. You'll need that.
  5. Jun 1, 2005 #4


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    The "gravitational force acting on the sphere" is just its weight. Look up the density of aluminum and multiply by the volume of the sphere. (The volume of a sphere of radius r is [tex]\frac{4}{3}\pi r^3[/tex].)
  6. Jun 1, 2005 #5
    HallsofIvy was correct, the gravitational force is just its weight, its simple

    use desnity of aluminium along with its volume to find the mass, then use this is W=mg formula to find the the weight force

    In terms of the pressure question, i know the area and velocity of the fluid at 2 points, its asking how much the pressure changes as it goes from one point to another.
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