My textbook says the an object undergoing undamped, under-driven(adsbygoogle = window.adsbygoogle || []).push({});

harmonic motion (http://romano.physics.wisc.edu/lab/manual/img279.gif)

doesNOThave its maxima at the points where the displacement

curve makes contact with the exponential envelope curve.

How can this be the case?? Doesn't the graph clearly imply that

the maxima are indeed the peaks of the decaying cosine curve (that

do make contact with the exponential wrapper)??

The text goes on to say that the maxima actually correspond not

to the x(t) vs. t plot -- but to the dx(t)/dt (the velocity) plot,

specifically where dx(t)/dt = 0. I can partially understand this since

at the maxima -- velocity does equal 0!

It then states that the displacement ratios between successive

maxima are constant.

I can see the constancy of the maxima ratios, but not the

basis on dx(t)/dt over the visual interpretation -- let alone

the assertion that successive maxima ratios are constant.

Comments? Thanks!

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# Basics of SHM (undamped, under-driven)

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