On Jul 29, 2007, at 1:44 PM, Harry Veeder wrote:
I know enough about the subject to admit error when I have not
made adequate use of Newton's laws of motion.
My statement is not aimed at admission of error if or when error is
made. It is about a method to help you discover and understand
principles for yourself, one that I use myself. I find it amazing
the number of times I start out writing a post only to discover it is
completely wrong. I think it is often the act of writing, of
struggling for clarity of expression and for clear justification
based on known principles, that leads to discovery. In the words of
David Melton, "The best ideas come from the work, not from our
heads." He was referring to writing in general, but I think it goes
double for physics.
Do you think the above prediction is not allowed by Newton's laws?
It is clear from your discussion that you don't understand angular
momentum, angular velocity, moments of inertia, and their relations.
An object in motion remains in motion unless acted upon by a force.
This goes for angular motion as well as linear motion. If you
suggest an object will change its angular (rotational) velocity then
it is essential to identify the source of the torque (angular force)
which does this. Things don't arbitrarily change their angular
velocity without a torque. There is no principle that states things
tend to seek a zero angular velocity with respect to the fixed stars
for example. Radial force won't change angular velocity either. Only
tangential force, which is known as torque. If you apply torque to an
object its angular velocity will change. There is only so much
energy you can get out of an object by breaking it using the moment
of inertia of another object. Soon they both rotate at the same
speed. The torque is equal and opposite to the opposed torque.
Again, I think of you try to write your predictions with full
justification and explanation for each step, using terms of angular
acceleration, angular velocity, torque, and moment of inertia, then
it may help you understand the principles. These terms are all
analogous to similar terms with regard to linear momentum, described
by Newton's laws, and the principles can be derived from Newton's
laws. Here are the correspondences:
acceleration: angular acceleration,
velocity: angular velocity,
force: torque: and
inertial mass: moment of inertia
If you think an angular velocity machine can produce free energy just
convert it into a linear machine to see why it won't work.
Horace Heffner
http://www.mtaonline.net/~hheffner/
