In the chapter summary (aka «glossary») on page 280 it says angular momentum is the capacity to make other objects rotate.
In addition to the causation issues mentioned in item #205, it is unhelpful to define angular momentum in relation to other objects.
Consider for example a universe consisting of a single object moving in a straight line. I can choose any datum I like; if I choose a datum that is offset from the particle's line of motion, the particle has a perfectly reasonable nonzero angular momentum ... utterly independent of any other objects.
Even if there are multiple objects, the angular momentum of one has got precious little to do with the rotation of the other objects. As an extreme case, consider N point particles all moving along the same straight line. Even if they collide, they cannot make each other rotate. If I choose a datum that is offset from the particles' line of motion, each particle has a perfectly reasonable nonzero angular momentum ... utterly independent of the other objects.
The idea is a loser coming and going. I can have two rigid bodies, each with initially zero angular momentum, that collide in such a way that each has nonzero rotation afterwards.
Other counterexamples are a dime a dozen.
The discussion as a whole, including the definition (if any) should emphasize the parallels between linear momentum and angular momentum. This alleged definition does not do that.
Suggestion:
There is a perfectly good definition of angular momentum in terms of linear momentum:
L = r ∧ p
This is independent of the other objects (if any), as it should be.
In the chapter summary (aka «glossary») on page 280 it says
angular momentum is the capacity to make other objects rotate.In addition to the causation issues mentioned in item #205, it is unhelpful to define angular momentum in relation to
other objects.other objects.other objects. As an extreme case, consider N point particles all moving along the same straight line. Even if they collide, they cannotmakeeach other rotate. If I choose a datum that is offset from the particles' line of motion, each particle has a perfectly reasonable nonzero angular momentum ... utterly independent of theother objects.Suggestion:
This is independent of the
other objects(if any), as it should be.