- #31
farolero
- 166
- 10
Dale said:
Yes they are coasting and doing zero work with their legs.
Problem with 2 cars on almost masless spining platform
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Discussion Overview
The discussion revolves around a theoretical scenario involving two cars on a nearly massless spinning platform. Participants explore the implications of the cars moving radially and then turning 90 degrees, particularly focusing on concepts of angular momentum, energy conservation, and reference frames.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
- Debate/contested
- Mathematical reasoning
Main Points Raised
- Some participants propose that the platform's mass can be neglected, while others argue that it cannot be assumed zero mass when applying unbalanced forces or torques.
- There is a discussion about the initial state of the platform, with some stating it is still and others questioning this assumption.
- One participant suggests that when the cars turn 90 degrees, the platform would start spinning in the opposite direction to maintain net momentum at zero.
- Concerns are raised about the frame of reference, with one participant expressing uncertainty about what constitutes an inertial frame.
- Another participant discusses the conservation of momentum and energy, questioning how these principles apply when changing frames of reference.
- There is a debate about the implications of frame dependence on kinetic energy, with examples provided to illustrate differing energy values based on the chosen reference frame.
- One participant notes that while energy and momentum are conserved, they are not invariant, leading to confusion when switching frames of reference.
- Another participant mentions the concept of "frame jumping," which can lead to errors in analysis when switching reference frames without proper consideration.
- A later reply introduces the idea that for a disk of finite mass, energy conservation holds, but for a zero-mass disk, the scenario becomes unphysical and undefined.
- There is a discussion about the limitations of the theoretical setup, with some participants questioning the physical feasibility of the scenario presented.
Areas of Agreement / Disagreement
Participants express multiple competing views regarding the assumptions about mass, reference frames, and the implications of the cars' movements on the platform. The discussion remains unresolved with no consensus on the physical validity of the scenario or the outcomes of the proposed actions.
Contextual Notes
Limitations include the dependence on the assumption of the platform's mass, the challenges of defining inertial frames, and the implications of energy conservation in a theoretical context that may not be physically achievable.
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