# Chapter 11 - Exercises and Problems: 57

25%

#### Work Step by Step

a) We find the final angular velocity: $\omega_f = \frac{(.044)(.035)^2}{(.044)(.035)^2+(.27)(.023)^2}\times180 = 140\ rpm$ b) We find: $percent \ lost = 100\times\frac{k_i-k_f}{k_i}$ Use the fact that $k=\frac{1}{2}I\omega^2$, it follows: $percent \ lost \approx \fbox{25%}$

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