How Does the Book's Formula for Angular Momentum Differ from Mine?

  • #1
Kashmir
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A disc initially has angular velocities as shown
IMG_20210707_220620.JPG

It's angular momentum along the y-axis initially is
I tried to find its angular momentum and ended up with this:The z component of angular momentum is thus

However I found a similar situation in a book
IMG_20210707_223058.JPG
IMG_20210707_221438.JPG


that writes the components of angular momentum along x as

The book has an additional term for the angular momentum which I don't.

Why am I wrong ?
 
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  • #2
Your question is not completely clear. Perhaps the disc is initially spinning with an and then given an additional rotation. Otherwise a magnetization of the disc could also make for an , but in general from any magnetization would be very small.
 
  • #3
Are you asking for an expression for the angular momentum of a disk where the rotation axis is not perpendicular to the disk? Your drawing is not clear.

Are and the cartesian coordinates of ? How are , and defined? Can you describe your calculations?
 
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