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Frictional Torque Questions

  1. Mar 19, 2008 #1
    Picture of situation has been attached


    The tension is not the only force producing a torque. There is also a frictional torque present that opposes the disk's motion (this is minimized by supporting the disk on a cushion of air). Use the "Top View" of the experiment in the simulation to answer the following questions.

    When the mass is falling, and the disk is speeding up, how does the direction of the frictional torque compare to the direction of the torque from the string?

    Same Direction or Opposite Direction

    When the mass is rising, and the disk is slowing down, how does the direction of the frictional torque compare to the direction of the torque from the string?

    Same Direction or Opposite Direction

    When is the magnitude of the disk's angular acceleration largest? When the disk is speeding up or when it's slowing down?

    Speeding up or Slowing down or Equal in both cases



    My guess is the following....

    1) and 2) Frictional Torque is the opposite direction because friction is always in the opposite direction of the force applied from gravity in this case.

    3) My guess is that the acceleration is greatest when disk is slowing down because the acceleration is coming from both the frictional torque and gravity, compared to when its speeding up, where the acceleration of gravity is positive and greater than the negative acceleration coming from the frictional torque.


    Can anyone please tell me if I'm right, and if my logic makes sense at all. Thanks.

    Kevin
     

    Attached Files:

  2. jcsd
  3. Mar 20, 2008 #2
    any help here please?
     
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