Lesson 38
Moment of Inertia Tensor, Principal Axes of Inertia

Name:faculty Section:M2 Start Time:16:28:9 Instructor:pate Course:355

1) Let's think about the moment of inertia tensor a bit more.

Mathematically, what is a "principal axis"? Physically, in your own words, what is it?

Consider the dunce cap (right cone shape) in the figure. What would be the principal axes for this cone? Please briefly explain how you arrived at your answer.



2) Consider the very thin blue rod of mass M, uniform density, and length L shown in the figure. The coordinates given by (x1, x2, x3) are located at the midpoint of the blue rod. If the moment of inertia of the rod about the X1 axis is given by (1/3)*ML2, predict the moment of inertia of the rod about the x1 axis. Please explain how you arrive at your answer.



3) When is it possible for one of the principal moments of inertia to exceed the sum of the other two?

  1. Never
  2. Always
  3. Sometimes



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