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Homework Help: Rotation (i need help badly)

  1. Nov 8, 2006 #1
    A wheel has a radius of 3.7 m. How far (path length) does a point on the circumference travel if the wheel is rotated through angles of 30°, 30 rad, and 30 rev, respectively?

    30° m
    30 rad m
    30 rev m

    I really need help on this. I dont even understand what im suppose to do because I dont really understand the question and from what the teacher told us had nothing or in anyway how to solve an equation like this.

    for the first equation i tried using this
    deltaTheta = w_initial*t + 1/2alphat^2 but then i realize i dont know what alpha or t is. so thats when i thought w_initial is 0 so

    deltaTheta = 1/2alpha*t^2 then i got this s = theta*r which will give me time in second but not sure.

    any help would be great and very helpful to my studying.
  2. jcsd
  3. Nov 8, 2006 #2


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    Homework Helper

    This question has nothing to do with angular velocity or acceleration. It is just to make sure you understand the various ways of expressing angular displacement.
  4. Nov 8, 2006 #3
    so to find the answer would i do this

    s = theta*r
    Vi = W*r
    a = alpha*r

    finding that using kinetic formula to get distance? deltax = Vit + 1/2at^2 and v^2 = vi^2 + 2adeltaX
  5. Nov 8, 2006 #4


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    I repeat....
    You have used one of the ways correctly.
  6. Nov 9, 2006 #5
    oh okay i got it now thanks for clearing that up.
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