释义 |
Simple Harmonic Motion Quadratic PerturbationGiven a simple harmonic oscillator with a quadratic perturbation ,
 | (1) |
find the first-order solution using a perturbation method. Write
 | (2) |
so
 | (3) |
Plugging (2) and (3) back into (1) gives
 | (4) |
Keeping only terms of order and lower and grouping, we obtain
 | (5) |
Since this equation must hold for all Powers of , we can separate it into the two differential equations
 | (6) |
 | (7) |
The solution to (6) is just
 | (8) |
Setting our clock so that gives
 | (9) |
Plugging this into (7) then gives
 | (10) |
The two homogeneous solutions to (10) are
The particular solution to (10) is therefore given by
 | (13) |
where
 | (14) |
and the Wronskian is
Plugging everything into (13),
Now let
Then
Plugging and (21) into (2), we obtain the solution
 | (22) |
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