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Homework Help: Copper ball

  1. Oct 16, 2007 #1
    Calculate the force required to pull a copper ball of radius 3.00 cm upward through a fluid at the constant speed 9.00 cm/s. Take the drag force to be proportional to the speed, with proportionality constant 0.950 kg/s. Ignore the buoyant force.

    For this question, do I have to find the mass of a copper ball first, right?
    Last edited: Oct 16, 2007
  2. jcsd
  3. Oct 16, 2007 #2


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    You've got an unknown force pulling up, and a drag force acting down. Anything else acting down?
  4. Oct 16, 2007 #3


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    Hello shiri, remember when the speed is constant we have the special case of 1st Law of Newton.
  5. Oct 16, 2007 #4
    if the net force is zero, so is that mean the copper ball is in a constant velocity?
    Last edited: Oct 16, 2007
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