Considering only Newtonian mechanics, what happens when two point masses collide?

JS

John Schoenfeld wrote:

Considering only Newtonian mechanics, what happens when two point masses collide?


No such thing--point masses! Unless you are referring to black holes... in
that case the two BHs would likely merge and Newtonian mechanics is not
adequate to describe the process.

Total force = Force_gravity - Force_friction
ma = mg alpha- Ff
a = g sin theta - Ff/m

where alpha is the trig factor to account for the component of
gravitational
acceleration down the slope. The main thing is it is a constant.

Notice the acceleration on the bicycle has the component due to
gravity and
that is independent of mass but the component due to frcition does
depend on
mass - the greater the mass, the lesser the effect of friction.

Hope this helps,

David Harris
About.com Physics Guide

*********

Sorry, that is bad math.

You have assumed the Ff is a constant without either stating or
defending that assumption, and it is not in fact correct. Ff is not
independent of m, whether you are sliding on a plane or rolling on
bearings. In either case, as m increases so will Ff. Look in any
engineering text on bearings and you will see by how much. Heavier
mass leads to heavier rolling resistance. If the experimental data is
correct, that heavier objects do roll faster downhill, you must
explain where the extra force to accelerate them comes from, because
the force of resistance due to friction does increase at least
slightly.

This is a case where the equations were solved correctly, but led to
an erroneous conclusion, and nobody applied the common sense test to
it. If that equation were correct adding weight would always reduce
friction, increase gas milage and efficiency, etc., and yet we know
that automotive engineers go to great lengths to reduce weight.

John Schoenfeld wrote:

Considering only Newtonian mechanics, what happens when two point masses collide?

Considering only Newtonian mechanics, it depends.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
"Quis custodiet ipsos custodes?" The Net!

John Schoenfeld wrote in message
om...

Considering only Newtonian mechanics, what happens when two
point masses collide?

JS

It depends upon the field potential. To prevent a fall to the center
for U(r) = - k / r (gravitational an Coulomb) potential, the orbital
angular momentum, L 0. For U(r) = - k / r^2 (no analogue in
Nature), L^2 2mk. In both cases, the fall to the center from
finite initial distance occurs in finite time. A potential with a repulsive
core, such as U(r) = + k / r^n, prevents a fall to the center for all L.

See "Mechanics" Landau & Lif****z ISBN 0 7506 2896 0

[Old Man]

(John Schoenfeld) wrote in message . com...
Considering only Newtonian mechanics, what happens when two point masses collide?

JS

According to Newtonian mechanics, the probability two point masses
would be at the exact same location at the same time ought to be
zero.

(ghytrfvbnmju7654) wrote in message om...
(John Schoenfeld) wrote in message . com...
Considering only Newtonian mechanics, what happens when two point masses collide?

JS

According to Newtonian mechanics, the probability two point masses
would be at the exact same location at the same time ought to be
zero.

If two macroscopic masses collide in a Classical experiment, then it
is just as well to say that their occured point mass collisions as
mass density is continuous across the volume of any body.

So what happens when two point masses collide in Classical physics?

Busted again in simple physics ...!
Knetic energy is CONVERTED to potentual energy .
The very FIRST thing is any colision is a rise of potentual energy OR
emf would not even exsist.
Then it will be conveted beck to kenetic energy OR it will be converted
to heat.
There are no exceptions and not one of you can squirm out of your
statments.
ITS bust #2 within 5 days . "" ON simple physics

I missed old man 's post ,,,Ill exclude him from the bust .

"tj Frazir" wrote in message
...
Busted.. .. ..

Preaching violence again?

Tsk, tsk.