Re: Need HELP



Cliff wrote:

On Sun, 25 Jun 2006 21:33:10 GMT, BottleBob <bottlbob@xxxxxxxxxxxxx> wrote:

Cliff:

And which direction does the momentum vector (or velocity vector),
point when the object in question is STATIONARY and has zero velocity
and therefor zero momentum within the reference frame considered, eh?
LOL

Only the magnitude (a scalar) may be zero, BB.
The momentum vector is still there. it did not suddenly become zero apples
in Lintland.

Cliff:

Huh? When the velocity drops to zero in the reference frame considered
there is no more velocity vector, and the momentum drops to zero with
it. That's just the way momentum works and is defined. This is high
school stuff. I guess yet another definition from a HS physics site
explaining this is in order:

========================================================================
http://www.physicsclassroom.com/Class/momentum/U4L1a.html

From the definition of momentum, it becomes obvious that an object has a
large
momentum if either its mass or its velocity is large. Both variables are
of equal importance
in determining the momentum of an object. Consider a Mack truck and a
roller skate
moving down the street at the same speed. The considerably greater mass
of the Mack
truck gives it a considerably greater momentum. Yet if the Mack truck
were at rest, then
the momentum of the least massive roller skate would be the greatest;
for the momentum
of any object which is at rest is 0. Objects at rest do not have
momentum - they do not
have any "mass in motion."
========================================================================

Nor should you forget that all possible reference frames exist at the same
time and any statement such as what you want to claim needs to be true in all
of them at the same time.

True in ALL reference frames simultaneously?? Excuse me? From your
statement above it seems you don't understand what the term "reference
frame" actually means in a classical mechanics context. Let me try to
help you out once again:

========================================================================
http://kwon3d.com/theory/transform/refrm.html

A reference frame is a particular perspective employed by the analyst to
describe and/or observe a motion effectively. There are different types
of reference frames. A fixed frame is a reference frame that is fixed. A
moving frame is a reference frame that moves with the body. A moving
reference frame can translate and/or rotate. When a reference frame is
either fixed or moving with a constant velocity, it is an inertial
frame. An accelerating reference frame is a non-inertial frame. A fixed
reference frame fixed to the environment, not to the moving subject, and
used commonly in describing the motions of different body parts is the
global frame while all the reference frames fixed to the moving body
parts are called the local frames.
========================================================================


========================================================================
http://en.wikipedia.org/wiki/Momentum

Momentum in classical mechanics

If an object is moving in any reference frame, then it has momentum IN
THAT FRAME. It is important to note that momentum is FRAME DEPENDENT.
That is, the same object may have a certain
momentum in one frame of reference, but a different amount in another
frame.
========================================================================

There may be many reference frames where the direction vector and
magnitude are opposite. To say that any statement must be
simultaneously true in ALL reference frames is not correct or possible.



I recently told you in another thread that mass is NOT inertia.

You wrote "Mass is the numerical measure of inertia."
So .... where's that peck of inertia?

Measure the mass, THAT'S your numerical "peck of inertia". That
doesn't mean it *IS* inertia, any more than a velocity of 75 mph *IS*
the car that is going that fast.


But
you don't seem to listen/remember/understand very well, or else you're
just playing at being obtuse for some obfuscating trolling effect.
Here, let me try to help you out once again with information from some
physics sites:

===============================================================
http://en.wikipedia.org/wiki/Inertia

Thus, "mass is the quantitative or numerical measure of body?s inertia,
that is of
its resistance to being accelerated".

Don't always trust Wick.

Pick any other physics site you wish, they'll probably all say
something very similar. If you doubt it, feel free to show any credible
ones that don't.

===============================================================
http://hyperphysics.phy-astr.gsu.edu/hbase/mass.html#mas

The mass of an object is a fundamental property of the object;

Mass is mass. What can I say?

Obviously not much of anything, since saying "mass is mass" is the
ultimate in circularity that defines/explains nothing at all. You may
as well say "Cats are cats", "hard is hard", or "metal is metal". Mass
has properties, it curves space, attracts other mass, has weight in a
gravitational field, has momentum when in motion, and has inertia.


a fundamental measure of the amount of
matter in the object.

Sort of like mass. I see. They have two terms but don't know which is which
yet you claim that it ony has "inertia" of it's not moving in YOUR referance
frame (see stuck rock).

I never would have said any such thing. Please find where I've ever
said that an object ONLY has inertia if it's not moving. Are you so
unable to support your position that you have to resort to the
fabrication of false statements of others?

Hence you are contradicting even these copied claims
(which I doubt you understand or you could use your own words for a change).

To my knowledge, I've contradicted nothing. Also, I use physics sites
to clarify and support my points with credible information. You should
try it sometime. In fact, I've asked you repeatedly to support your
WAG's and opinions with credible physics sites when you've stated that
mass and time are vector quantities or that mass ALWAYS has momentum
(even if it's stationary). But I have yet to see you show ANY such
credible support at all. Now why might that be? LOL


--
BottleBob
http://home.earthlink.net/~bottlbob
.

Relevant Pages

  • Re: OT The Politcal Brain - Confirmation bias
    ... Cliff wrote: ... Scalar multiplication with the zero vector yields the zero vector: ... magnitude of zero momentum units. ... mass and zero velocity - how much momentum does it possess? ...
    (alt.machines.cnc)
  • Re: collision
    ... The trick is to transfer to the centre of momentum frame for the ... This is a frame in which the total momentum is zero. ... each mass. ...
    (sci.physics)
  • Re: Machinists; critical machining data
    ... momentum, even if that momentum happens to be zero. ... Cliff and I do a little dancing Minuet on certain subjects. ... not be an intrinsic property of mass - and even mass may not be an ... But NO motion = zero momentum. ...
    (alt.machines.cnc)
  • Re: Two-thirds of Republicans rejected Darwins theory
    ... since I SPECIFIED a particular reference frame - and within that SPECIFIED reference frame the stationary bowling ball has ZERO momentum since it had ZERO velocity within the SPECIFIED reference frame. ... Inertia is the resistance of an object to a change in its state of motion. ...
    (alt.machines.cnc)
  • Re: Need HELP
    ... Momentumis momentum, BB. ... Mass is mass. ... within the reference frame considered. ... moving frame is a reference frame that moves with the body. ...
    (alt.machines.cnc)