Spring-type questions

dmahler
Posts: 50
Joined: Mon Sep 15, 2008 9:15 am

Spring-type questions

Postby dmahler » Sat Sep 20, 2008 3:05 pm

Hey guys, I've been doing the practise tests and I see at least 2 questions having to do with multiple springs, normal modes etc. Does anyone have any suggestions on where to read about this? I was taught this stuff at one point, but its a little hazy. Thanks,
-Dylan

dmahler
Posts: 50
Joined: Mon Sep 15, 2008 9:15 am

Re: Spring-type questions

Postby dmahler » Sat Sep 20, 2008 4:37 pm

Sorry to do this, but I have one more question. Anyone have a good text they use for Electronics questions? And electromagnetic theory?
Those are the three types of problems I am currently weak in, springs, electronics, and E&M. For spring stuff I am currently using Young and Friedman, for electronics I am winging it, and for E&M I am using Griffiths (this may be huge overkill). Any help would be great. Thanks,
-Dylan

dmahler
Posts: 50
Joined: Mon Sep 15, 2008 9:15 am

Re: Spring-type questions

Postby dmahler » Mon Sep 22, 2008 9:33 pm

No one? Especially the spring-type questions.
-Dylan

Juston
Posts: 31
Joined: Mon Sep 01, 2008 6:15 pm

Re: Spring-type questions

Postby Juston » Mon Sep 22, 2008 11:38 pm

I was never strong with normal modes myself, but a good text to refer to for a lot of classical mechanics stuff is the one by Taylor. However, from what I remember from the practice tests, some of the pendulum problems only required a qualitative understanding of the normal modes, so I'm thinking that you may be able to eliminate answer choices by first developing a mental picture of what the normal modes look like.

For electronic circuits, I look at my freshman physics texts (Serway, Giancoli). A modern physics text (or an extended version of a freshman text like Halliday/Resnick) is good for things like semiconductors, diodes, transistors and stuff. For E&M, Griffiths is the best, but I agree that it's overkill.

sravanskarri
Posts: 58
Joined: Sat Jun 14, 2008 10:19 pm

Re: Spring-type questions

Postby sravanskarri » Mon Aug 24, 2009 10:39 pm

@mahler:
If you are still looking for some good references on normal modes. Check the open courseware video lectures from MIT ( Physics 2: Vibrations and Strings ). Dr.Walter Lewin explains these very well.

nathan12343
Posts: 249
Joined: Sat Dec 20, 2008 9:34 am

Re: Spring-type questions

Postby nathan12343 » Tue Aug 25, 2009 4:27 am

One of the best ways to do these types of questions is to write down the Lagrangian of the system and solve for the normal modes by using the Euler-Lagrange equations. This reduces the problem to taking a few derivatives and doing some algebra. Also, the method described on the wikipedia page on Normal Modes (substiuing solutions of the form e^(iwt) and then solving for w) would probably be applicable if you can write down equations of motion for whatever masses are in the problem.

A good reference for this material would be Thornton & Marion.




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