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Thread: Math plus Physics [Picture!]

  1. #1
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    Default Math plus Physics [Picture!]

    This time, I included a picture, with the accurate measurements!



    I wanted to make this as good to understand for Yohojo, so I made a remake.




    And finally, in words.

    The sprockets and chain of a bicycle are shown in the figure. The pedal sprocket has a radius of 4 in., the wheel sprocket a radius of 2 in., and the wheel a radius of 13 in. The cyclist pedals at 40 rpm.

    a) Find the angular speed of the wheel sprocket.
    b) Find the speed of the bicycle. (Assume that the wheel turns at the same rate as the wheel sprocket.)


    Thanks,

    EDIT: Explanation also, if possible. I need to explain to my people.

    hakuna matata ;)

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    done, taking picture

    edit:
    alright, let's see if I did anything correctly

    http://i48.tinypic.com/eukdwm.jpg

    Looking at the picture, first off, convert RPM to rad/s, that is the angular velocity of the first sprocket.
    Then, simply use a ratio to find the angular velocity of the second sprocket, assuming the chain between the two is rigid, and does not stretch.
    Then angular velocity times radius gives you tangential velocity, convert to a common unit such as mph.
    Last edited by Brain; 01-15-2010 at 03:55 AM.
    Proud owner of "Efferator" my totally boted main account!
    "You see, sometimes, science is not a guess" -Xiaobing Zhou (my past physics professor, with heavy Chinese accent)

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    I suppose this is extremely easy. But since I'm taeching it to the whole class I'm paranoid simple physics won't work.

    Haha, thanks Brain.

    hakuna matata ;)

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    lmao, easy to find, i'm doing this atm =D but sorry can't explain this in english LMAO lol
    Sorry for my bad english, i'm french

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    the big sprocket will turn at (pi*D*rpm)/60 so in this case (3.14*4*40)/60 this is the speed in inches per second the speed of the small sprocket must be the same so it is the speed/ circumference ((3.14*4*40)/60)/(pi*4) this give rpm of small sprocket this is the same rpm as wheel so times by circ of wheel to find speed of wheel and therefore bike

    (((3.14*4*40)/60)/(pi*4))* pi*13 this is speed in inches i have no idea the conversion factor to meters which is the standard SI unit at my uni thats what they expect answers in dont know about where you are though

    its late i would hate to be incorrect but it does happen

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