I fail to see how two counterrotating gyroscopes behave

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Discussion Overview

The discussion revolves around the behavior of two counterrotating gyroscopes, particularly in configurations such as a V shape and their implications for angular momentum and resistance to spin. Participants explore theoretical aspects of gyroscopic motion and conservation of momentum in a space environment.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant assumes that two counterrotating gyroscopes offer no resistance to spin, suggesting they behave as if they are not spinning.
  • Another participant questions this assumption, proposing that two counterrotating gyros set in a V shape would have a net angular momentum and could exhibit precession if subjected to torque.
  • A different participant argues that once the gyros are in a V shape, no external force acts upon them, implying they could maintain that position indefinitely.
  • Another contribution emphasizes that angular momentum is a vector and suggests adding the vectors of the counterrotating gyros to determine the total angular momentum vector.
  • One participant acknowledges a misunderstanding regarding their original assumption about the behavior of V-shaped gyros, indicating that they can still spin around one axis of space.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of counterrotating gyroscopes and the implications of their configurations, indicating that multiple competing views remain and the discussion is unresolved.

Contextual Notes

Participants do not fully explore the implications of angular momentum vectors or the conditions under which the gyroscopes maintain their configurations, leaving some assumptions and dependencies unaddressed.

farolero
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so my assumption is that 2 counterotating gyros offer nor resistance to spin, its like they were not spinning

but two counter rotating gyros set in a V shape will offer resistance in all axes of space

so an astronaut in space has the arm aiming up and in each hand he has two counterotating gyros

net momentum is zero

now the astronaut puts his arms in cross and now the gyros are spinning in the same sense so to keep the conservation of momentum the astronaut begins to spin in opposite sense

but imagine a mid point the astronaut put the arms in a V shape

now to keep momentum he begins to spin vertically

but then what happened with the V shape two gyros resistance to spin since the astronaut is spinning with them

anybody know what would be going on here?
 
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farolero said:
so my assumption is that 2 counterotating gyros offer nor resistance to spin, its like they were not spinning

but two counter rotating gyros set in a V shape will offer resistance in all axes of space
Examine that assumption for a moment. Two rotating gyros set in a V shape will have a net angular momentum, yes? This angular momentum will have an associated direction, yes? If the frame on which the two gyros are mounted is subject to a torque about an axis aligned in that direction, would you expect to see any precession?
 
well but once the gyros have the V shape no more force is acting upon them, you could even set them free from each other and theyll keep that V position
 
farolero said:
anybody know what would be going on here?
Angular momentum is a vector. Add the vectors of the counter rotating gyros to get the total angular momentum vector.

For another example, see below video for co-rotating gyros on a counter rotating V. The total angular momentum here happens to be zero:

 
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i see thanks a lot i see my original assumption was wrong, two V gyros still can spin in one axe of space
 

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