/sci/ - Science & Math

Anybody actually know what the fuck the "reversed effective force" in d'Alembert's principle is?

As in this definition http://www.britannica.com/EBchecked/topic/150132/dAlemberts-principle

ITT: Things from Classical Mechanics you never really understood.

>>5787213
It's suppose to be a survey book and there isn't any "advanced classical mechanics" in it either. (Read Goldstein if you think otherwise.) The E&M (statics/dynamics/circuits) is at the same level as the Mechanics section and does the job for non-majors.

You can't really attack it for the lack of QM and Relativity since they really need more advance Algebra and Analysis than the students reading it know so they really can only cover the basic concepts.

>>5787245
But it's aimed at HS kids and freshmen without much or any exposure to physics or mathematical maturity so some amount of excess hand holding is in order. If you're really bored with it then just jump straight into Talyor's Mechanics, Griffiths' E&M, and Shankar's Quantum books. No one forces you to follow the same path as everyone else.

>>4700666
>energy can not be created nor destroyed.

Wrong.
Your notion of energy is pretty childish. Conservation of energy is a derived law, that only applies to certain types of systems.

>>4207104
Goldstien

>>2532437

1) Set up two body problem, obtain equations of motion for moon and earth.

2) Fill one body (earth) with liquid, use perturbation theory to find new equations of motion

3) PROFFIT! You have now have the equations governeing how the moon affects the tides and shit.

Anything else?

>>2349848
>>2349848

Yes, that is an example. However, it can happen in classically 'closed' systems as well.

It is possible to construct a 'classical closed' system that depends explicitly upon time.
Chapter 2.7 goes into it in great detail.

>>2210112

Ok, sorry, I guess I got off point.
Yeah, by far the most fundemental tools you need to start off with in physics, are Lagragian and Hamiltionan Mech.

These will give you the ability to simplify physical systems, by generalizing ideas like mometum or energy, etc. You will eventually be able to create your own versions of mometum, position, energy, times...as you see fit, however the fuck you want. Ie, mometum becomes "momenta".

You should eventually be able to realize that it isnt the "defintions" that matter, but the way the concepts relate to one another. It will give you a great ability to abstract physics, in a way you may not have thought possible before.

If you never learn how to do that, you will not make it to anything more advanced. I reccommend Marion and Thorton. Good luck!

>>1299072
Yeah, we have tons.
Any Hamiltonian that depends of t, doesnt conserve energy. Its basic Mechanics.

Yeah, you dont understand "homogenity of time". What you are talking about is the cpt shit (the t) violation and shit like that.

Here this is a good book, on basic mechanics.