Damped Harmonic Motion - Oscillating Spring

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Homework Help Overview

The discussion revolves around a problem related to damped harmonic motion, specifically focusing on the oscillation of a mountain bike's shock absorbers. The original poster presents a scenario involving the calculation of the spring constant based on given parameters, including the period of oscillation and the mass of the bike and rider.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the spring constant using the period of oscillation and the mass. Some participants question the interpretation of the quality factor and its impact on the calculations. Others suggest that the natural frequency should be reconsidered in light of the quality factor.

Discussion Status

Participants are actively engaging with the original poster's calculations, offering insights and corrections regarding the interpretation of the quality factor and the natural frequency. There is a recognition that the initial computation may not fully account for the damping effect indicated by the quality factor.

Contextual Notes

Some participants express difficulty accessing external links provided by the original poster, which may limit the context of the problem. The quality factor is noted to be 10, which is considered significant in the context of the problem.

elemis
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Homework Statement



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).

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:
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Might be OK but I can't read what it said in parentheses after " ...bad shock absorbers ...".
 
rude man said:
Might be OK but I can't read what it said in parentheses after " ...bad shock absorbers ...".

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:
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.
 
rude man said:
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.

7045cz9au1ci7cdfg.jpg
 

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