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Homework Help: Angular Acceleration of a bicycle

  1. Oct 20, 2008 #1
    A bicycle has wheels of 0.8 m diameter. The bicyclist accelerates from rest with constant acceleration to 22 km/h in 13.7 s. What is the angular acceleration of the wheels?

    relevant equations:
    omega = omega initial + alpha * t

    22km/h = 6.11m/s

    I did 6.11m/s * 13.7s = 83.7207 to get the velocity
    then I divided it by .4m to get 209.30175
    Im not sure what I should do next

    I have another question which is related to the same topic:
    A block of 2kg falls with a speed of 3.9m/s from rest to a distance of 2.5m, its acc. is 3.0m/s from a pulley of radius of 8cm.

    (b) What is the angular velocity of the pulley at this time?
    I used V = R/omega
    = 3.9m/s = .08m / omega
    omega = .02
    This is wrong is my approach wrong?
    Last edited: Oct 20, 2008
  2. jcsd
  3. Oct 20, 2008 #2


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    Homework Helper

    First convert km/h to m/s = 1000/3600

    v = 22 kmph = 6.1 m/s

    w = v/r = 6.1/.4 = 15.278 radians

    w = a*t => a = w/t = ... ?
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