(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Determine the eigenfrequency of the disc with mass m = 20 kg of fig. 11-38. Assume that the disc doesn't slides.

http://img80.imageshack.us/img80/8408/86061698.jpg [Broken]

2. Relevant equations

The correct answer is 1.01.

3. The attempt at a solution

If the angle [tex] \theta [/tex] is measured in radians then the distance travelled downwards is [tex] R \cdot \theta [/tex], now Newton in the direction of the spring leads to:

[tex] m R \ddot{ \theta} + k R \theta = 0[/tex]

Thus the eigenfrequency is:

[tex] \omega = \sqrt{ \frac{kR }{mR} } = \sqrt{60} [/tex]

[tex]2\pi f= \omega \rightarrow f= \frac{\sqrt{60} }{2 \pi} = 1.23 Hz.[/tex]

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# Homework Help: Eigenfrequency calculation

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