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Fluids( Pressure)

  1. Oct 10, 2011 #1
    The volume of a cone of height h and base radius r is V = πr2h/3. A jar
    in the shape of a cone of height 25 cm has a base with a radius equal to 15 cm.
    The jar is filled with water. Then its lid (the base of the cone) is screwed on and
    the jar is turned over so its lid is horizontal. (a) Find the volume and weight of the
    water in the jar. (b) Assuming the pressure inside the jar at the top of the cone is
    equal to 1 atm, find the excess force exerted by the water on the base of the jar.
    Explain how this force can be greater than the weight of the water in the jar.

    I don't understand part b.
    Do they want me to find Fexcess= Fg-1atm/areaOfBase ?

    I get for part a:
    V=5.9 Liters

    Thank you.
  2. jcsd
  3. Oct 10, 2011 #2
    The excess pressure at the bottom of the jar is rho*g*h. If you calculate the force on the bottom of the jar, you'll get something considerably larger than 59N.
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