Re: Conservation of angular momentum

On Jun 7, 8:55 am, Peter <Poakfi...@xxxxxxx> wrote:
On Jun 6, 6:39 pm, PD <TheDraperFam...@xxxxxxxxx> wrote:





On Jun 6, 3:19 pm, Peter <Poakfi...@xxxxxxx> wrote:

On Jun 6, 9:41 am, PD <TheDraperFam...@xxxxxxxxx> wrote:

On Jun 6, 8:19 am, Peter <Poakfi...@xxxxxxx> wrote:

On Jun 5, 5:47 pm, PD <TheDraperFam...@xxxxxxxxx> wrote:

On Jun 5, 4:09 pm, Peter <Poakfi...@xxxxxxx> wrote:

Yes, that is right, the wheels haveangularmomentum, but the
particles of the exploding mixture have only linearmomentum, which
the engine converts intoangularmomentum. Don't you think so?

No, and this is where your confusion about terminology gets in your
way again. A particle traveling in a *straight line* certainly does
haveangularmomentumwith respect to a reference point not on that
line, according to the physics books you have in your possession. It
is certainly NOT true that only particles traveling in curves can haveangularmotion. That is YOUR interpretation of that word, but it is
NOT the meaning that physicists ascribe to that word. The definition
that *physicists* use is completely self-consistent, but it does not
match up to the meaning you ascribe.

PD

You are right, according to the standard definition, but not only
that, a particle traveling in straight line also obeys Kepler's second
law. Please see:http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=147.0

Peter

Two comments:
- Kepler's laws were meant to apply to conic section orbits and no
planet travels in a straight line. So the fact that something that was
NOT INTENDED to be covered by Kepler's 2nd law is in fact still
covered, tells you something about the fundamental nature ofangularmomentum.
- Since you have acknowledged that something you thought was wrong is
in fact right, this should serve as an indicator to you of two things.
a) Not everything you forced yourself to "unlearn" should have been
unlearned, and you need to un-unlearn them. b) Perhaps some of the
other things you think are wrong are in fact right, and it might do
you good to start again and rethink things. Right now, you're in a
blind alley.

PD-

The fact that a particle traveling is a straight line obeys Kepler's
second law, tells me that this law may well be a geometrical curiosity

Actually, no, not just a geometric curiosity. It has fundamental
physical meaning.

that has nothing to do withangularmomentum. Besides, I understand
that "torque" necessarily means: a force in the direction of motion,

No, it does NOT.

If not the direction of motion, what direction has the force applied
through a torque?


That depends on the situation. There are many examples in your
textbook where a torque is not in the direction of motion, as well as
many examples where a force is not in the direction of motion. Torque
can be applied in ANY direction.

PD

.

Relevant Pages

  • Re: Conservation of angular momentum
    ... A particle traveling in a *straight line* certainly does ... NOT the meaning that physicists ascribe to that word. ... NOT INTENDED to be covered by Kepler's 2nd law is in fact still ...
    (sci.physics)
  • Re: Conservation of angular momentum
    ... A particle traveling in a *straight line* certainly does ... NOT the meaning that physicists ascribe to that word. ... NOT INTENDED to be covered by Kepler's 2nd law is in fact still ...
    (sci.physics)
  • Re: Conservation of angular momentum
    ... A particle traveling in a *straight line* certainly does ... planet travels in a straight line. ... NOT INTENDED to be covered by Kepler's 2nd law is in fact still ...
    (sci.physics)
  • Re: Conservation of angular momentum
    ... A particle traveling in a *straight line* certainly does ... NOT the meaning that physicists ascribe to that word. ... NOT INTENDED to be covered by Kepler's 2nd law is in fact still ...
    (sci.physics)