Moment of Inertia of square based pyramid?

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SUMMARY

The moment of inertia of a regular square pyramid with base length 'a' and height 'b' about its axis of symmetry (z-axis) can be calculated using the volume and center of mass of the pyramid. The discussion emphasizes the importance of considering the pyramid as a stack of square slabs rotated about their center to derive the correct formula. Participants noted consistent discrepancies in their calculations, often due to missing factors in their equations. The correct approach involves integrating the contributions of each slab to achieve an accurate moment of inertia.

PREREQUISITES
  • Understanding of basic geometry and calculus
  • Familiarity with the concept of moment of inertia
  • Knowledge of volume and center of mass calculations
  • Experience with integration techniques in physics
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  • Study the derivation of moment of inertia for various geometric shapes
  • Learn about the integration of mass distributions in three dimensions
  • Explore the concept of rotational dynamics and its applications
  • Investigate the use of software tools for calculating moments of inertia
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Students in physics or engineering courses, particularly those focusing on mechanics, as well as educators seeking to enhance their teaching of rotational dynamics concepts.

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Homework Statement


A regular square pyramid (base length a, height b) is spun about its axis of symmetry z.
Calculate its moment of inertia about the z axis

Homework Equations


volume of pyramid
centre of mass


The Attempt at a Solution


have found volume and centre of mass. I know the answer to the moment of inertia but when i try to get to it I am always out by factors.
 
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Try looking at it as a stack of square slabs rotated about their center.
 

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