Transcript here

‫بسم هللا الرحمن الرحيم‬
Coupled Oscillations
Zain Yamani
Saudi Physical Society
Rabi-I, 1433
Agenda for Lecture-7:
1.
2.
3.
4.
5.
Administration..
General theory of oscillations
Double-pendulum
CO2 molecule oscillations
A few comments about the homework
Administration
What I have posted on the course web-site
As a next interaction, I want you to help me beef up the
“Relevant Web-sites” section of my course page.
We are approaching the end.. 
Oscillations..
• SHO (at mass connected with a spring to a rigid wall)
• Connecting the mass to more than one spring (parallel/ series)
• Simple pendulum
• Harmonic Oscillator for two (same or different) masses connected with a spring
• Two masses connected to opposite walls without coupling
• Two masses connected to opposite walls with (weak/ strong) coupling
• The special case when the coupling is ineffective (through special initial conditions)
• The general case of “n” masses in 3-D.. (3n – 6)  in linear: (3n-5)
• Two pendula hanging from one another  esp. the special case when they act as one
swinging pendulum (through special initial conditions)
• Three masses (as in CO2 molecule)
• The role of symmetry and the importance of Group Theory
• Coupled oscillator (two dipoles) as in solid state physics and the 6-12 potential
Oscillations..
• The general case of “n” masses in 3-D.. (3n – 6)  in linear: (3n-5)
T, V: what are the Ajk and mjk?
See notes..
Non-degenerate, first 
two coupled oscillators.nb
Check the weak coupling case 
Play with the code, at home..
Double Pendulum
• Two pendula hanging from one another  esp. the special case when they act as one
swinging pendulum (through special initial conditions )
Note that the T-1 M is not orthogonal
Do you remember the four masses connected with springs on the rim
of a circle??!
Oh.. Oh!!!! we have degeneracy!
Let’s take a step back to mathematics (linear algebra) and see how we
deal with degeneracy.
Oscillations..
• Three masses (as in CO2 molecule)
The general case of “n” masses in 3-D.
3 Translation, 3 (or 2??) rotation and the rest [(3n – 6)  in linear: (3n-5)] vibration
modes
Let’s concentrate on longitudinal modes!!
What about the transverse modes?
What do we intend to do next Session?!!