Talk:Classical mechanics
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Gareth, I like some of what you've done, but I'm a bit disappointed with the resulting formatting changes. In previous versions, each concept had a separate, dilineated section with information presented in a concise, organized manner. This was useful for quick reference. Your version is more precise and reads better than earlier versions, but is less useful as a quick reference. My recommendation is to add a separate page titled "Equations of Classical Mechanics" or "Summary of Classical Mechanics", which will basically be a table of the various important equations in classical mechanics.
The page should start with definition equations for the various key parameters (eg. velocity, acceleration, force, work, kinetic energy, momentum, angular momentum, etc...). This section could then be followed by a listing of other useful equations, like x=1/2at2+v0t+x0. What do you think?
--Matt Stoker
Thanks for the praise. The "Equations..." page sounds like a really good idea - GWO
Personally, I would prefer defining force at least initially as, F = m*a, however, if the consensus is that F=d(m*v)/dt is more precise,
I phrased it like that for a few reasons. Its a more literal "translation" of what Newton said, you do need it for some problems (the pendulum drop sand, rocket burning fuel...) and (last and least) it fits with the concepts of relativistic mechanics (4-momenta and all that) better -- GWO
would it be preferable to first define momentum as p=m*v and then define force as F=dp/dt?
--Matt Stoker
Yes, it would be better. That way you can keep the same definition of force in relativity.
Could be. Weigh up the addition of some more notation, with the simplification of some of the equations. Would it obscure the logical flow behind F=d(m*v)/dt=m*dv/dt=m*a ? I guess the notation thing is the age-old problem of mathematical writingGWO
Just did a major overhaul of the classical mechanics equations. Mostly I added a few equations here and there, made vector quantities bold, and changed the format to be more friendly with bold vector quantities.
Moved the request: Someone please add the equations for gravitational, electric, and magnetic forces
to this page, and responding. Gravitational may be appropriate, but electrical and magnetic force definitions belong with articles on electricity and magnetism (believe me, they're another whole ball game).
Final note: physicists divide physics in to classical and quantum mechanics. Einstein's relativity is actually lumped in with classical.
- I'm not sure it's so cut and dried. I know there are quantum mechanical approximations that are based on "classical mechanics" and then if necessary relativistic corrections are tacked on.--Matt Stoker
- On that topic, I came here to find out what the "opposite" of Newtonian Mechanics is so I could link it from Aerodynamics but there seem to be many different fields; now I'm confused. Could someone tell me what the field is when one can no longer assume conservation of mass and conservation of energy? moink 23:04, 26 Dec 2003 (UTC)
- You can always assume conservation of energy; however in relativity conservation of mass is an approximation
I've gutted the article and re-written major parts of it. It's still far from complete, but I'm structuring it after quantum mechanics, which I think has a very nice layout. Some of the removed material probably ought to be stuck back in, either here or in a separate article.
Comments are welcome. Hope I haven't ruffled any feathers :-P
Some changes, with reasons:
- Removed the description of SI units. They ought to go into the respective nodes for force, mass, and so forth; in my opinion they are distractions from the presentation of the theory.
- Removed most of the examples, but I want to put them back in somewhere. Some of the examples were rather disorganized, e.g. discussing the effects of gravity without having introduced gravitation. Also, Newton's law of gravitation is quite independent of the formal structure of classical mechanics, and that wasn't coming through properly.
Ultimately, I think we'll want to have links to the important sub-topics of classical mechanics: composite objects, inertial and non-inertial reference frames, oscillations, and so forth. -- CYD
Einstein long ago presented us with a radical new way to view the universe. His mathematical calculations and theories harbored destruction for the current theories of the time. The theories focused on objects such as: Planets, Galaxies, Nebulae, Gravity. Next, came Quantum Physics. These mathematical calculations and theories focused on the tiny world. Atoms, Quarks, Protons, Neutrons, Electrons...
Now, In their own right, each of the theories are correct. But, when the two theories had to be combined mathematically, they were incompatible; the math would spit out nonsense.
Recently, a new theory called string theory has surfaced. The book by Brian Greene, called The Elegant Universe, explains the theory. When positioned "between" these two theories, it can connect the two; making them compatible, and causing another revolution.
Rockets/physics type stuff
Hi, I need a bit o help. See, in my science class we're making rockets (out of pop bottles, but still). We can add wings, weights, etc., and the point (the part we get graded on) is to get them to go up about 20 feet (which I can do) AND to get them to go straight up and straight back down w/in 5 ft. I think of where we launched it from. Any ideas @ all on how to do this? Thanks a bundle! I don't know how often I'll be checking back here, so my e-mail is DFINEDFINE1@aol.com Thanks, much! ~~Taylor
Could someone explain how a problem involving a changing mass would sound such as decreasing rocket propellant or something like that. I'm just trying to get a feel for this since up till now I've just understood Newton's Second Law as F=ma or F=m(dv/dt). From the Newton's Laws of Motion page I got the equation F=ma+v(dm/dt) for calculating the force with a variable mass, is this right? thanks - James
examples section
It appeared that the examples section had been the result of several clashing writers, so I tried to clean it up and get a good explanation for the galilean transformation, which I think is what was trying to be explained before by the standard two cars example.
Small copyedit
In this sentence, Classical mechanics can be used to describe the motion of human-sized objects (such as tops and baseballs), many astronomical objects (such as planets and galaxies), and certain microscopic objects (such as organic molecules.) ... wouldn't it be better to replace "human-sized objects" without a more accurate, less ambiguous phrase--baseballs are NOT the size of humans. Perhaps we could say something like "objects easily perceived and manipulable on the human scale"...I'm not a great wordsmith, someone help me out 70.57.137.163 04:44, 8 Apr 2005 (UTC)