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Homework Help: Help me please. Radian (question 15)

  1. Oct 19, 2014 #1
    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

    3. The attempt at a solution
    a) α = Δθ / Δt

    Can we please go over each option?

    OK looking at option a, it does give me an alpha so I don't know what to think of this. Then it says (Alpha = Change of angle/change in time). This seems to be the formula for "angular velocity" but what is alpha? can we go over this first? what is alpha?
  2. jcsd
  3. Oct 19, 2014 #2


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    Science Advisor
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    Gold Member

    a) and b) are typos. a) should be "##\omega=##" and b) should be "##\alpha=##". ##\alpha## is angular acceleration.
    Does the answer make sense now?
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