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Homework Help: Finding angular speed/accel from tangential speed

  1. Oct 7, 2007 #1
    1. The problem statement, all variables and given/known data

    Professional recording studios often use reel-to-reel tape decks. On such a tape deck, the tape is pulled past the playback head at a constant linear speed of 0.381 m/s. (a) Using the data in part a of the figure, find the angular speed of the take-up reel. (b) After 2.79 x 10^3 s, the take-up reel is almost full, as part b of the drawing indicates. Find the average angular acceleration of the reel with the appropriate sign, where a positive value means the reel is speeding up.


    2. Relevant equations

    Vtangential = r*omega (which here will be w)
    accelerationtangential = r*alpha (here,alp)


    3. The attempt at a solution
    .381 m/s = r * w rad/s

    In the diagram, r isn't given. Is there a way I can find it? It's constantly changing because of the tape's reeling effect, so I'm not sure how that would fit in.
     

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  2. jcsd
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