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Homework Help: Velocity and maximum height

  1. Feb 3, 2005 #1
    a 3 gram mass is projected vertically upward from the earth's surface at an initial velocity of 1000 cm/sec and moves through a medium that offers a resisting force of 3 |v|. how long does it take to reach its maximum height? assume w = mg, where g = 9.80.

    i started by using m*(dv/dt) = m*g*R^2/(x+R^2)

    but i don't know how the 3|v| resistance factors into it.
     
  2. jcsd
  3. Feb 3, 2005 #2

    HallsofIvy

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    Science Advisor

    The force acting on the object is -mg-3|v|, the gravitational force and the retarding force from the medium so m(dv/dt)= -mg-3|v|.

    I don't know where you got your formula.
     
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