# Chapter 13 - Exercises and Problems - Page 239: 41

.69 seconds

#### Work Step by Step

We must find the period of the oscillations: $T = \frac{2\pi}{\omega}=\frac{2\pi}{\sqrt{\frac{k}{m}}}=\frac{2\pi}{\sqrt{\frac{2.2}{.43}}}=2.78 \ sec$ We know that $\pi/2$ is one quarter of a period, so it follows: $t = \frac{2.78}{4} = \fbox{.69 seconds}$

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