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Homework Help: Finding ang vel

  1. Nov 10, 2007 #1
    Electric toothbrushes can be effective in removing dental plaque. One model consists of a head 1.10cm in diameter that rotates back and forth through a 70.0 angle 7600times/min . The rim of the head contains a thin row of bristles. its asking me the average angular speed in each direction of the rotating head.

    w=7600times/min(1min/60s)6.28rad/1rev= 795.49rad/s

    but it says im wrong what am i doing wrong?
    Last edited: Nov 10, 2007
  2. jcsd
  3. Nov 10, 2007 #2


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    It rotates through 70deg 7600 times /minute not a full circle.
    so thats 70 * pi/180 radians in 60/7600 seconds.

    It could also be double that if it means it goes +70deg then back to the start 7600 times a minute?
  4. Nov 10, 2007 #3
    yea it would be double since its going back and forth thanks
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