A great demonstration on gyroscopes

[jasc15]

This guy, Walter Lewin, is a physics professor at MIT. I found this series of lectures on youtube a few years ago. This lecture in particular relates to rotating bodies, and if you go to 43:50, he has a nice demo of the gyro's application in INS, but the principle is exactly the same in the other gyros on your plane.

http://www.youtube.com/watch?v=zLy0IQT8ssk#t=43m50s

 

[jhausch]

Damn You - I'm not going to get any work done this evening now!
:wink2:

 

[bigred177]

So, when he puts the weights on the gyro will it slow down faster than if there was no weight on it? It seems it would be taking energy to resist the down force put on the gyro.

 

[jasc15]

So, when he puts the weights on the gyro will it slow down faster than if there was no weight on it? It seems it would be taking energy to resist the down force put on the gyro.

In theory, no, If I understand it correctly. But in reality, the bearing friction is increased as a result of those weights, so it would slow down more quickly.

 

[gismo]

So, when he puts the weights on the gyro will it slow down faster than if there was no weight on it? It seems it would be taking energy to resist the down force put on the gyro.

If the system is frictionless, the answer is no. But unless the gyro is spinning in a vacuum with magnetic bearings there will be friction in the gimbals, the rotor support, and in the air's resistance to the rotor spinning and precessing. Motion and friction imply work and the energy for that work has to come from somewhere (hint: spinning the rotor required work input which gets stored as energy in the rotating inertia of the wheel).