Physlet Illustration: Torque and Moment of Inertia

 

 

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A mass (between 100 and 1000 g) is hung by a string from the edge of a disk-like pulley causing it to accelerate as shown. The time is shown in seconds and the angular velocity, omega, is given in radians/sec. Determine the mass of the pulley.

Hints

  1. Pause the animation at several times and determine the angular acceleration of the pulley.
  2. Next determine and the linear acceleration of the mass. (How is this related to the angular acceleration?  Determine the radius of the pulley!)
  3. From Newton's Second Law for translational motion, determine the tension in the string.
  4. How much torque does this tension provide to the pulley?
  5. Use the angular acceleration and torque to determine the moment of inertia, and hence the mass of the pulley.
  6. How should the behavior of the system depend upon the hanging mass?

Reference

See Walker, Section 11-2

Illustration written by Chuck Niederriter