- #36
DrStupid
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PeterDonis said:In other words, you spin up the assembly to some angular velocity, and keep it constant while you measure the sensor signal. Then you spin the assembly up some more, and hold it constant again while you measure the sensor signal. Then you repeat until you have enough points for a graph. Correct?
Exactly.
PeterDonis said:Then you have the following problem: how do you correlate the different angular velocity measurements? A spin-up process intervenes between each one, and that process will change the spatial geometry of the assembly (because it will change the internal forces within the assembly, since those forces depend on angular velocity). That includes possible changes in the relative alignment of the slits; in other words, the equilibrium state of the assembly at different angular velocities may have different alignments of the slits.
In steady rotating state the change of spatial geometry is radial symmetric and would therefore not affect the relative alignment of the slits.
PeterDonis said:Also, you are still either assuming that the entire assembly has a single "co-rotating rest frame" for each angular velocity measurement
This is not just an assumption. There is always a frame of reference where the assembly has no angular momentum.
PeterDonis said:(so an angular velocity measurement at one point applies to the entire assembly)
This is given when any part of the assembly has a constant angular momentum in the common rest frame. Indeed I still assume that the assembly will always reach such a state of steady rotation if it is sufficiently balanced to remain radial symmetric.