Action for the harmonic oscillator
In the figure you can choose different mathematical trajectories in the
configuration space for the harmonic oscillator:
d2x/dt2
+ ω2 x = 0.
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Unit mass is that of the oscillator.
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In the left panel you can choose the frequency ω, the
starting and ending configurations (t1,x1) = (t1,x1)
and (t2,x2) = (t2,x2),
as well as the number of points N in the polygonal trajectory
and. The trajectory points, including the end points, can be moved
with the mouse.
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To get information on the other elements, put over them the mouse
pointer to see the corresponding tooltip.
Activities
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Use the mouse to move around trajectory points, including end points.
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At each time the action along the current trajectory is shown in blue
and, if Physical is selected, the minimal action along the
physical trajectory between the two end points in red.
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You should be able to check Hamilton's principle of least action:
the value of the action along the trajectories joining two
configurations reaches its minimum precisely along the physical
trajectory.
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The physical trajectory corresponding to the current two end points is
recovered when pressing Set solution.
This is an English translation of the Basque original for a course
on mechanics, oscillations and waves.
It requires Java
1.5 or newer and was created by Juan
M. Aguirregabiria with Easy
Java Simulations (Ejs) by Francisco
Esquembre. I thank Wolfgang Christian and Francisco Esquembre for
their help.