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Sliding vs. rolling ball

  1. Nov 28, 2008 #1
    hi there!

    I considered the following problem:

    a ball of radius R on a horizontal plain is at first in rest. Then it receives a horizontal force for a very short time at a point placed 1/3R from the plain and the ball starts moving with initial velocity v_0. There is also a friction when the ball slides.

    the question is: at which velocity v will the ball start rolling?

    here´s what I figured out:

    the force initiates a torque such that the ball gets initial angular velocity w_0, counter clockwise. But the velocity v initiates another angular velocity w in clockwise direction. My assumption is that the ball will start rolling counter clockwise when the velocity v becomes 0.

    what do you think?
  2. jcsd
  3. Nov 29, 2008 #2
    any comments are welcome :)
  4. Nov 30, 2008 #3


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