# Chapter 9 - Exercises and Problems - Page 166: 91

a) $\frac{M}{a+1}$ b) $x_{cm}=\frac{ML}{2+a}$ c) These are not surprising, for they are the equations for when a rod is uniform, which is the case when a=0.

#### Work Step by Step

a) We know that the mass is the integral of the equation over the length of the rod: $m = \int_0^L \frac{Mx^a}{L^{1+a}}dx=\frac{M}{a+1}$ b) $x_{cm} = \int_0^L x \frac{Mx^a}{L^{1+a}}dx$ $x_{cm} = \int_0^L \frac{Mx^{1+a}}{L^{1+a}}dx$ $x_{cm}=\frac{ML}{2+a}$ c) These are not surprising, for they are the equations for when a rod is uniform, which is the case when a=0.

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