Moment of Inertia: Pendulum Problem

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SUMMARY

The forum discussion centers on calculating the moment of inertia for a pendulum system consisting of a rod and a disc. The participants utilize the parallel axis theorem (PAT) and specific formulas for moment of inertia, including I = 1/3ML^2 for the rod and I = 1/2MR^2 for the disc. Key calculations reveal that the total moment of inertia is approximately 44.65 kg·m², correcting earlier miscalculations. The discussion emphasizes the importance of ensuring all components are calculated about the same axis and understanding the derivation of moment of inertia equations.

PREREQUISITES
  • Understanding of moment of inertia concepts
  • Familiarity with the parallel axis theorem (PAT)
  • Knowledge of basic physics equations for rotational motion
  • Ability to perform unit conversions and dimensional analysis
NEXT STEPS
  • Study the derivation of moment of inertia equations, particularly I = 1/12MR² and I = 1/3ML²
  • Learn about the perpendicular axis theorem and its applications
  • Practice problems involving the parallel axis theorem with different geometries
  • Explore advanced rotational dynamics concepts, including torque and angular momentum
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and rotational dynamics, as well as educators seeking to clarify concepts related to moment of inertia and its calculations.

  • #31
I'd also try and derive the moment of inertia expressions from I = \int\!r^2 dm. It's a fun little exercise that will help you understand why the expressions are as they are. It will also show you the power of the parallel axis theorem. There's also the perpendicular axis theorem, which I recall doesn't get much exposure in introductory mechanics classes.
 

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