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Homework Help: Can someone explain this to me please?

  1. Dec 9, 2014 #1
    • Warning: Non-descriptive thread title
    1. The problem statement, all variables and given/known data
    Which equation is valid only when the angular measure is expressed in radians?
    a) α = Δθ / Δt

    b) ω= Δω / Δt

    c) ω^2 = ωo^2 + 2αθ

    d) ω = Vt/r (here T is a subscript)

    e) θ = 1/2αt^2 + ωαt

    Answer is D but why??

    2. Relevant equations

    I know angles can be measured in either degrees or radians

    3. The attempt at a solution

    angular velocity = ??? divided by radius

    I guess I don't understand what Vt is
  2. jcsd
  3. Dec 9, 2014 #2
    How do you relate the length of an arc to the angle subtended by the arc and the radius? What should the units of each quantity be?
  4. Dec 9, 2014 #3


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    Staff: Mentor

    Presumably ##V_t## will be defined in the text surrounding the problem. In this context I would imagine that it represents the tangential velocity of a rotating object at distance r from the center of rotation.
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