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Homework Help: Rotational Motion

  1. Feb 28, 2007 #1
    1. The problem statement, all variables and given/known data
    A solid sphere with mass "m" and radius "r", slides (without rotating) on a frictionless horizontal surface, with speed of V[0].

    At time t[0] the sphere roll on a surface with friction "u", at time t[0] the ball is starts rotating as it glides aswell. At time t[1] the ball only rotates.

    2. Relevant equations

    What is the balls center mass velocity as a function of time, from time t[0] to time t[1].

    3. The attempt at a solution

    I have been trying to take a look at the balls inertia and torque on the ball from the friction. But the only result I got was that the ball gains speed, an that is nonsence.

    Plzz... help this is a homeasignment that comes down on my final grade.
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 28, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    You probably have the torque going in the wrong direction. In any case, consider the translational motion.

    Hint: What forces act on the sphere? Note that the sphere is slipping. Apply Newton's 2nd law.
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