16.8 Exercise 8

Engineering Application: A suspension bridge oscillates with an effective force constant of $1 . \text{00} \times \text{10}^{8} \text{N}/\text{m}$. (a) How much energy is needed to make it oscillate with an amplitude of 0.100 m? (b) If soldiers march across the bridge with a cadence equal to the bridge’s natural frequency and impart $1 . \text{00} \times \text{10}^{4} \text{J}$ of energy each second, how long does it take for the bridge’s oscillations to go from 0.100 m to 0.500 m amplitude?