"YOU CAN'T FIGURE OUT HOW PHYSICS WORKS BY JUST THINKING ABOUT IT... UNLESS YOU'RE ISAAC NEWTON"

Okay, so, you're saying that if you're the right person you CAN figure out physics just by thinking about it.

More ivory-tower-ism... Yet with an acknowldgement that people CAN make valid observations and/or useful predictions just by thinking about it. Love the irony and the contradiction of it all.

Point being that many thing we know were the results of "thinking" and not simply "doing math." I mean, physics doesn't proceed from math, math is a tool used to describe physical processes once the process has been observed and thought about (I'm more in the roundabout observing and thinking stage and haven't gotten to the hard math stage; might get there oen of these days once the watching and thinking subsides). Newton didn't think: F=M*A therefore an apple drops. More like, "okay, an apple dropped, now WHY did it drop? What factors played in to causing the apple to move from being stationary attached to the tree into motion, to impacting my head, bouncing, dropping some more, hitting the ground, then stopping?"

That's the problem with string theory and a bunch of other scienticians and mathemagicians getting together to try to "mathematize" physics. You get a bunch of gibberish nobody understands and which really doesn't describe anything real or make any useful/verifiable predictions. *Sigh* Ohh well. For some reason it just feels like we've got it backwards, and nowadays we're writing the math before we have thought about or understood the underlying process. And that's just back assward, for lack of a better term, from the way Newton most likely did it (observe, understand, write math). You can't do the math until you know WHAT you're doing the math OF, or the math is only theoretical and NOT useful/pratical (under most circumstances)... Just my opinion of course.

I mean what good is math and a physical model that we can't understand in terms of every-day or REAL things? Just wondering.

Science is a process of OBSERVATION, measurement, understanding, writing a model, testing the model, observation, measurement, understanding, etc. etc. But it starts with observation and understanding NOT with math. Math is only useful once there is understanding and for replication.

Opps, skimmed and missed this note:
"I NEVER SAID THAT. PHYSICS IS ALL ABOUT OBSERVATION. MATH IS JUST FOR THE BOOKEEPING"

I agree with that. But, it seems like you've been saying that math is the only way to go about physics. But I agree with you so long as you agree that math is for book-keeping, but physics itself is about observing and understanding in relatable terms we can actually understand.

I also agree with your statement:

"WITH THE MATH AND THE UNIT DEFINITIONS YOU CAN DO PRECISE CALCULATIONS WHICH CAN BE TESTED IN THE LAB."

Math is simply a more precise language (as long as it's used correctly, and there are no typographical errors or miscommunication/misunderstandings). But it must proceed from a more fundamental real-world understanding or it is useless (as you seem to agree, physics needs observations to motivate the equations). IE, we need to understand what we are describing with the equations, or else the equations lose their meaning. That's part of my initial inquiry, to understand what the equations mean in ACTUAL reality, rather than simply in a line of letters, numbres, and mathematical symbols. Math is a representation in language, of a process or of a thing. I seek the real-language equivalent description of what the math-language says.

There should really be a rosetta stone to translate between math-language and natural-language, as it were. And there should be some level of equivalency.

"YOUR CONFUSION ABOUT UNITS IS A PROBLEM EVERY FIRST-YEAR PHYSICS STUDENT HAS TO COME TO GRIPS WITH, SINCE IT DOESN'T MAKE SENSE THAT SUCH DIFFERENT PHYSICAL PROPERTIES ARE CONNECTED. JUST ACCEPT IT AS A BOOKEEPING CONVENTION. THE PROOF THAT IT WORKS COMES FROM THE LABORATORY, WHEN YOU START SEEING HOW THESE PROPERTIES CAN BE MEASURED AND THEN PREDICTED."

Ehh, that's bordering on the Ex Cathedra. "It works because we say it works... Just accept it and move on." That's kind of papal authority argument that science was supposed to get rid of. Am I wrong?

I mean, it kind of sounds like "We don't know why it works, it just works, so just accept it." Kind of like the Earth-centric models of the heavens that were subsequently supplanted by modern notions of a heliocentric solar system rotating around the sun and another system centered on the center of the galaxy, possibly more systems centered on the middle of the local cluster (remains to be seen how the universe works as a whole)?

Not trying to be a smart ass. Though I suppose maybe I come off a bit like it. Sorry 'bout that. I do appreciate the info and stuff. :)

"UNITS ARE DEFINED FOR PHYSICAL QUANTITIES BECAUSE THEY SHOW US HOW TO CORRECTLY COMPUTE WITH THEM. WE SAY MOMENTUM IS A NUMBER ASSOCIATED WITH A CERTAIN MASS TRAVELING AT A CERTAIN SPEED. WE CALCULATE THE MOMENTUM BY MULTIPLYING THE MASS TIMES THE VELOCITY (I.E., A 0.05 KG BULLET TRAVELING AT A 1000 M/S HAS A MOMENTUM OF 50 KILOGRAM-METERS PER SECOND. THE MOMENTUM UNIT DOES NOT HAVE A NAME HONORING SOME DEAD PHYSICIST, BUT THAT IS JUST HISTORY AND TRADITION, NOT PHYSICS.
THE REASON WE DO THIS IS SO WE CAN USE THIS UNIT IN COMBINATION WITH OTHER QUANTITIES. FOR EXAMPLE, ONE DEFINITION OF FORCE IS "THE TIME RATE OF CHANGE OF MOMENTUM". SO IF YOU DIVIDE MOMENTUM BY TIME, YOU GET FORCE, SINCE THE DEFINITION OF FORCE IS KILOGRAM METERS PER SECOND SQUARED. ANOTHER DEFINITION OF FORCE, MASS TIMES ACCELLERATION ALSO COMES OUT IN THE SAME UNITS."

Okay, so if I understand right, oh tutor, my tutor, the multiplying of mass by velocity isn't really predicated on a physical process so much as just trying to get mass into the equation in the way that best fits with other math...?

It's essentially just saying that we know velocity at any point, we know the change in velocity or acceleration at any point, we know the direction (part of velocity), and now we also know the mass. And in some manner some or all of these can be interchanged... Insofar as one total force number can be achieved by varying up the mass and down the acceleration, etc. etc.

IE, the same force accelerates a 5Kg object to 10,000 meters/second in one second as accelerates a 10,000Kg object to 5 meters/second in one second, yeah? Is that right?

T=Time
D=Distance
Kg=Mass
V=Velocity
M=Momentum
A=Acceleration
F=Force
E=Energy
P=Power

V = D/T

M = Kg * V
or M= Kg * (D/T)

A = V/T
or A = D/(T^2)

F = Kg * A
or F = M/T
or F = (Kg * (D/T))/T
or F = Kg * (V/T)
or F = Kg * (D/T^2)
or F = Kg/T * D/T

E = D * F
or E = D * Kg * (D/(T^2))
or E = Kg * (D^2)/(T^2)
or E = Kg/T * (D^2)/T

So, anyway, one could say that, in terms of momentum:

M = 5Kg * 10,000meters/second
is equivalent to
M = 10,000Kg * 5 meters/second

since multiplying them together, we still get 50,000 Kg-m/s.

Seems weird that the momentum of these objects is the same, but the math seems equivalent, yeah?

So the forces involved must also be equivalent, right? Since force is just momentum over time? IE, if something has a momentum of 50,000 Kg-m/s and we're dividing that by time, the equation simply becomes 50,000 KG-m/(s^2).

Does that sound right? And am I right in assuming then that the force required to bring a 5Kg mass to 10,000 meters/second in one second is equivalent to the force needed to bring a 10,000Kg mass to 5 meters/second in one second?

So, two objects of 5Kg and 10,000Kg will be differently affected by the same force? IE, One (5Kg mass) will be accelerated to 10,000 m/s whereas one (10,000Kg) will only be accelerated to 5 m/s by the same force (50,000 Kg-m/s)? Or likewise an object 50,000Kg will be accelerated to 1 m/s by the same force?

So, for example (thought experiment only, I know it wouldn't work this way in reality; or would it?) if a rock of 5Kg, were traveling 10,000 miles per hour, and hit an asteroid at rest with a mass of 10,000Kg and transferred all of its energy to the asteroid and the 1Kg rock stopped dead in the exchange, would it be enough of an impact/energy transfer to accelerate the asterod to 5 meter/second? Likewise, if an asteriod of 10,000Kg were moving at 5 m/s, hit a rock (5Kg) and stopped dead, would the rock go whizzing off at 10,000 meters/second? Is that essentially what we're saying with the equivalence in the equation (ignoring the fact that obviously in neither instance would the rock or asteroid transfer 100% of its motion and stop dead)?

(In thinking about that, would that mean that different objects in a gravitational field [like Earth's] would be accelerated at different rates based on their mass? I thought that different objects dropped at the same time were accelerated evenly by gravity regardless of weight/mass? Am I mis-interpreting things, or does the above seem to violate that principle? IE, if gravity is a "force" and a force acts on somethgin based on its mass, shouldn't objects with different mass be affected or accelerated differently? If so, why do we say that in an ideal situation a bowling ball and a feather would hit the ground at the same time? Or is there more that factors into it the equation tha just mass and acceleration, or momentum and time? Again, for some reason we seem to be getting counter-intuitive. Sorry, I hate to make more stuff for ya' to explain. ;o] Of course any insight is appreciated.)

You mentioned earlier in your post:

"IN NEWTONIAN MECHANICS, MASS IS DEFINED TO BE THAT PROPERTY OF MATTER WHICH RESISTS ACCELLERATION. IT DOES NOT INCREASE WITH THE VELOCITY OF THE MASS. iN RELATIVISTIC MECHANICS, THE MASS DOES INCREASE WITH VELOCITY, BUT THIS IS NOT MEASURABLE AT THE NORMAL SPEEDS OF OUR EVERYDAY EXPERIENCE ..."

IE, dont' get them confused.

But to some degree it already seems to be confused a bit... And I guess I'm confused as to why we need to learn Newtonian stuff before relativistic stuff. If relativity is correct, why aren't we simply taught that instead? Newton says mass doesn't vary with acceleration. Einstein disagrees. They can't both be right. Those are mutually exclusive principles. It's can't both change and not change at the same time. Either it changes or it doesn't change. In that regard, either Newton is right and we should learn Newton, or Einstein is right, and we should learn Einstein. That seems to be a stumbling block. IE, we talk about "mass" but are we talking about it in Newtonian terms, or Einsteinian terms? And do we understand what mass actually *is* or simply its effects? IE, we say that mass is the resistance to acceleration. But do we know what mass is such that it causes a resistance to acceleration? What's the root cause?

So, I guess my question is still kind of one of effect vs cause. Mass is resistance to change in velocity, so what is the physical structure or material that causes this resistance? Getting right down to it, I guess that's what I'm asking. How is mass structured? What's the underlying process/material that makes an object with it resist acceleration?

In another post, I kind of worked out that I figured it was based on an object's ability to absorb and then re-transmit energy. The better an object could absorb and re-stransmit, the better it could resist acceleration due to imparted energy. IE, if re-emission of energy is equal to or greater than imparted energy, the net acceleration is zero or negative. Only as an object is unable to emit sufficient energy versus that imparted does the internal energy go up, thus acceleration occurs along the overall direction of imparted velocity/energy. So, one might say that the higher the energy input versus an objects ability to re-emit that energy, the more the imparted energy will tend to accelerate the object...

So, one might say that if an object is hit by 2 joules/second, but only has the ability to re-emit energy at 1 joule/second, then that extra joule/second gets "caught up" in the object and imparts energy into the object, quite possibly causing acceleration... Or something to that effect. Once the input power source terminates, the object continues to re-emit at 1 joule/second until it reaches equilibrium again...? Dunno if that makes sense, just seemed like a decent off-the-cuff hypothesis.

Anywho, thanks for all the help! :)