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Homework Help: Circular Rotation Question

  1. Oct 11, 2004 #1
    A disk of radius .12 m starts accelerating from rest at 8 rad/s^2 At t = 5s

    A)What is the Angular Velocity
    This one is easy.. Av = 8rad/s^2*5 = 40 rad/s
    And makes sense.

    B)What is the tangential Accel?The book gave answer of .96 m/s^s Therefor, i assumed that the equation is At = w*r w=omega which is 8 rad/s^2 * .12m = .96 m/s^2

    However, later I found an equation for At given as At=dv/dt
    What gives? Which equation is correct for Tangential Accel? If they are both correct then how would I use At=dv/dt?


    Thanks
     
  2. jcsd
  3. Oct 11, 2004 #2
    Both are correct,

    Remember dv/dt is nothing but d(r*Av)/dt and since r is constant r*d(Av)/dt
    which is nothing but r*w... which was the first equation you used...
     
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