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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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    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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