I fail to see how two counterrotating gyroscopes behave

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In summary, two counterotating gyros will not offer any resistance to spin, as they cancel each other's momentum. However, when set in a V shape, they will have a net angular momentum and offer resistance in all axes of space. This can be seen when an astronaut in space holds two V-shaped gyros in each hand and spins in the opposite direction to maintain conservation of momentum. When the astronaut changes the orientation of the gyros, such as placing them in a cross or vertical position, the resistance to spin will change accordingly. The total angular momentum of the gyros can be calculated by adding the individual vectors.
  • #1
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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  • #2
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?
 
  • #3
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
 
  • #4
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
 

FAQ: I fail to see how two counterrotating gyroscopes behave

1. How do two counterrotating gyroscopes behave?

When two gyroscopes are counterrotating, they will have opposite directions of rotation. This means that they will exert equal and opposite torques on each other, causing them to remain stable and maintain their orientation.

2. What is the purpose of using counterrotating gyroscopes?

One of the main purposes of using counterrotating gyroscopes is to cancel out any external forces or torques acting on the system. This allows for more accurate measurements and stable behavior.

3. Do counterrotating gyroscopes have any practical applications?

Yes, counterrotating gyroscopes are commonly used in navigation systems, such as in airplanes and spacecraft, to maintain a stable orientation and accurately measure changes in position and direction.

4. Can counterrotating gyroscopes be used in other fields besides navigation?

While their main application is in navigation, counterrotating gyroscopes can also be used in other fields such as robotics, where they can help stabilize and control movements.

5. Can two counterrotating gyroscopes ever become unstable?

While counterrotating gyroscopes are designed to maintain stability, there are certain conditions that can cause them to become unstable, such as external disturbances or incorrect alignment. It is important to properly calibrate and maintain the gyroscopes to prevent instability.

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