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Damped Harmonic Motion - Oscillating Spring

  1. Apr 8, 2013 #1
    1. The problem statement, all variables and given/known data

    http://www.mediafire.com/view/?7045cz9au1ci7cd

    A mountain bike has bad shock absorbers (w0/γ = 10) that oscillate with a period of 0.5 seconds after hitting a bump. If the mass of the bike and rider is 80kg, determine the value
    of the spring constant k (remembering that there are two springs that share the mass equally).

    3. The attempt at a solution

    2pi/0.5 = w = 4pi But w = √(k/m)

    16pi2 * 80 = k = 12633.

    Since the two springs are in parallel we have the spring constant for an individual spring = 6317 N/m
     
    Last edited: Apr 9, 2013
  2. jcsd
  3. Apr 8, 2013 #2

    rude man

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    Might be OK but I can't read what it said in parentheses after " ...bad shock absorbers ...".
     
  4. Apr 8, 2013 #3
    Its basically saying that the quality factor = 10

    Could I have another opinion, please ?

    Here's the entire question if you need it :

    http://www.mediafire.com/view/?7045cz9au1ci7cd
     
    Last edited: Apr 9, 2013
  5. Apr 9, 2013 #4

    rude man

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    Couldn't open the link. But, no matter, you said Q = 10.

    Which is a pretty high Q but still the fact that it's not infinite means your computation of k is off by a bit.

    You first need to compute your natural frequency which = sqrt(k/m). Hint: it's not 2pi/0.5 rad/s. Close, but not equal to.

    Use your knowledge of Q to get the natural frequency & then you're home free.
     
  6. Apr 9, 2013 #5
    7045cz9au1ci7cdfg.jpg
     
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