Units and the Cross Product

  • #26
Thank Tiny-Tim. Well, when a math teacher is discussing area you would have units specified, for example. :)
But surely physics more so.

So is a cross product vector just another way of stating the answer to a normal physics question
"What is the angular momentum of such and such given the following conditions?"
And the vector in words would be stated
(whatever the magnitude is) metres squared per second?
ie
Vector C is 38 meters per second squared
AND the answer to the physics question just happens to be pointed in 3D space along the axis of rotation?
So you could almost imagine the vectors or whatever they mean rotation around the cross product vector as if it's really an axis of rotation? Or is it merely symbolic with no correlation to a physical rotation around that vector?
I'm going to understand this Cross product thing in real world terms if it kills me. lol
 
  • #27
Oh I should have added...

(whatever the magnitude is) metres squared per second along an infinite amount of vectors all parallel to each other angled in a specific way to the 3D coordinate system.
 
  • #28
tiny-tim
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… the answer to the physics question just happens to be pointed in 3D space along the axis of rotation?
So you could almost imagine the vectors or whatever they mean rotation around the cross product vector as if it's really an axis of rotation?
You can think of angular momentum as pointy and thin, in which case it's one-dimensional,

or you can think of as circular , in which case it's two-dimensional.

It's the same question as for a rotation …

is a rotation about a line or in a plane?

you can define it either way. :smile:
 
  • #29
Take for example a gyro.
Once spinning, is it resistance to positional change of the axis that keeps the top upright if started upright? And is that resistance because of the rotating mass around the axis? Can this be defined with vectors as well?
 

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