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12.37 (12.39)
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12.63 (12.65)
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13.36 (13.34)
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13.56 (13.54)
13.62 (13.59)

13.42
The human eye and muscles that hold it can be modeled as a mass-spring system with typical values m= 7.6 g and k= 2.6 kN/m. What's the resonant frequency of this system? Shaking your head at this frequency blurs vision, as the eyeball undergoes resonant oscillations.

13.47
The protein dynein powers the flagella that propel some unicellular organisms. Biophysicists have found that dynein is intrinsically oscillatory, and that it exerts peak forces of about 1.0 pN when it attaches to structures called microtubules. The resulting oscillations have amplitude 13 nm. If this system is modeled as a mass-spring system, what's the associated spring constant?If the oscillation frequency is 65 Hz, what's the effective mass?