- #1
nonequilibrium
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Hello, I quote http://en.wikipedia.org/wiki/Precession from the first paragraph from the first section ("Torque-free precession"):
But isn't the matrix product L = Iωs relative to the moving frame (that's how we did it in our course anyway), meaning L and omega are indeed the vectors as defined/seen from the absolute/fixed frame, but the matrix product has the components from the moving/relative frame. In that case, those components of L don't have to be fixed, since a fixed L in the absolute frame will seem to be rotating/changing when seen from the moving frame.
For example, when a plate is thrown, the plate may have some rotation around an axis that is not its axis of symmetry. This occurs because the angular momentum (L) is constant in absence of torques. Therefore it will have to be constant in the external reference frame, but the moment of inertia tensor (I) is non-constant in this frame because of the lack of symmetry. Therefore the spin angular velocity vector (ωs) about the spin axis will have to evolve in time so that the matrix product L = Iωs remains constant.
But isn't the matrix product L = Iωs relative to the moving frame (that's how we did it in our course anyway), meaning L and omega are indeed the vectors as defined/seen from the absolute/fixed frame, but the matrix product has the components from the moving/relative frame. In that case, those components of L don't have to be fixed, since a fixed L in the absolute frame will seem to be rotating/changing when seen from the moving frame.