Physics Confusion - Angular Velocity

Discussion in 'General Off-Topic Chat' started by jonthedit, Dec 16, 2014.

  1. jonthedit
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    jonthedit GBAtemp Advanced Maniac

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    Hi again guys, I am back with a bit of confusion in Physics again... sorry about that.
    I was able to do everything in my homework except this one problem.


    Your bicycle tires have a radius of 0.33 m. It takes you 850 seconds to ride 14 times counterclockwise around a circular track of radius 73 m at constant speed. (a) What is the angular velocity of the bicycle around the track?

    [bike]r = 0.33m
    2pi*.33

    [track]r = 73m
    2pi*73*14 (14 times around)

    Wf = Wi + a*t
    Wf^2=Wi^2+2a*changeoftheta
    changeoftheta=Wit+.5*a*t^2

    I am unsure where to start other than finding the circumference. :|
    Please help, I need to understand this. I feel like I am missing something obvious, because I figured out how to do all the other angular velocity problems.
     
  2. Fat D

    Fat D GBAtemp Maniac

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    All the radii are pointless. You just need the period. Think of what an angle 14 full counterclockwise rotations are, and think of how big an angle you thus move ahead every second.
     
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  3. bobmcjr

    bobmcjr GBAtemp Advanced Fan

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    Ignore the bike tire radius.
    (2pi*73m*14)/850s=7.554m/s
    To get the angular velocity, just divide the linear velocity above by 73m to get 0.103 (rad)/s
     
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  4. jonthedit
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    jonthedit GBAtemp Advanced Maniac

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    I am such a moron! Thanks a bunch guys! I just got freaked out about the radius.
    :|
    I've been doing that on the other ones, can't believe I just assumed it wasn't the same.