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Particularly when studying angular momentum, which requires motion in at least two dimensions.vanhees71 said:
Problem with understanding angular momentum
- Context: Undergrad
- Thread starter mohamed_a
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Discussion Overview
The discussion revolves around the understanding of angular momentum, particularly in the context of elastic collisions and the behavior of objects in circular motion. Participants explore the relationships between mass, radius, velocity, and kinetic energy, as well as the implications of conservation laws in these scenarios.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
- Mathematical reasoning
Main Points Raised
- One participant expresses confusion regarding the angular momentum equation (mrv) and its dependence on radius, questioning how different radii affect the velocities of colliding spheres.
- Another participant challenges the initial formulation of angular momentum, suggesting that the centers of rotation must be the same for valid comparisons.
- There is a proposal that the conservation of kinetic energy might be more applicable in certain cases, especially in elastic collisions.
- Some participants discuss the behavior of a stick attached to a pivot, raising questions about how angular momentum conservation applies to different parts of the stick and their velocities.
- Concerns are raised about the implications of moving mass closer to the pivot and how this affects angular velocity and speed, with some participants asserting that angular momentum conservation leads to increased speed as mass is retracted.
- One participant introduces the concept of exerting force to change the motion of a particle in a circular path, suggesting that this can lead to increased speed as the particle moves inward.
Areas of Agreement / Disagreement
Participants do not reach a consensus on the best approach to understanding the problem, with multiple competing views on the applicability of angular momentum versus kinetic energy in different scenarios. The discussion remains unresolved with ongoing questions and challenges to various claims.
Contextual Notes
Participants highlight the importance of defining reference points for angular momentum calculations and the conditions under which conservation laws apply. There are also discussions about the assumptions underlying the behavior of rigid bodies and the effects of external forces.
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