Would the friction be in the plane?

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    Friction Plane
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Discussion Overview

The discussion revolves around the dynamics of two disks, one rotating and the other dropped onto it, focusing on the role of friction and torque in their interaction. Participants explore concepts related to angular momentum conservation and the effects of friction in this context.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant posits that the two disks come to the same angular speed due to friction, questioning the absence of torque action on the system.
  • Another participant clarifies that while the system of disks experiences no net torque, each disk individually does experience torque due to friction.
  • A subsequent participant seeks to understand the implications of torque in relation to the conservation of angular momentum, specifically questioning if individual torques exist without affecting the overall system.
  • A later reply confirms the previous assertion that individual torques are present, but they do not result in net torque on the system of disks.

Areas of Agreement / Disagreement

Participants generally agree on the principle that the system of disks has no net torque, while acknowledging that individual torques act on each disk. However, the nuances of how these concepts interrelate remain a point of discussion.

Contextual Notes

The discussion involves assumptions about the nature of friction and torque, as well as the conditions under which angular momentum is conserved. Specific definitions and conditions for torque and friction in this scenario are not fully resolved.

Alem2000
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If you had two disks with the lower one rotating and dropped the one on top onto it they both come to the same angular speed b/c of friction. How come there is no torqu action on it? Would the friction be in the plane?
 
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What exactly do you mean when you say "there is no torque action on it?"

If there is friction then eventually the two disks will rotate at the same rate and it will do so in conformance with the principle of angular momentum conservations since there is no net torque on the system of disks. However, and obviously, each disk will experience torque.
 
Okay what I don't understand is ...the conservation of angular momentum requres there to be no net torque...so are you saying that individually there is a torque but not on the system of the two disks?
 
Last edited:
That's exactly what I am saying! :-)
 

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