Angular Momentum: Formula Comparison & Usage

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Homework Help Overview

The discussion revolves around the topic of angular momentum, specifically comparing two formulas: L = r x p and L = Iw. Participants are exploring the contexts in which each formula is applicable and the differences between them.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the appropriate contexts for using each formula, with one questioning the application of L = Iw for a rotating rod. There is also a focus on understanding the significance of the moment of inertia in relation to the axis of rotation.

Discussion Status

The conversation has progressed with some participants gaining clarity on the distinctions between the formulas. Guidance has been provided regarding the use of L = Iw for non-point particles, specifically in the case of a rod rotating about an end.

Contextual Notes

There is an emphasis on ensuring that the moment of inertia used is appropriate for the specific object and axis in question. Participants are navigating the nuances of angular momentum definitions and applications.

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I have two formulas to find angular momentum, and I am not sure when to use one and when to use the other, or what the difference is between the two. One is L = r x p, and the other is L=Iw.
 
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The former is used for a the angular momentum of point particle about some point, while the latter is used for the angular momentum of an object rotating about a fixed axis.
 
Last edited:
ok, I understand now. Thanks
 
so, if it's a rod, for example, rotating about one of its ends, I should use L=Iw?
 
Given that a rod is not a point particle, yes.

Just be careful to note that the moment of inertia (I) you are using is for that object about the given axis.
 

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