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[Phys-l] Classical Adiabatic Invariant



I'm attempting to understand this as applied to a simple pendulum. The examples I've found apply to shortening the rod. Wherein E/omega is a constant. Shortening the rod increases the frequency, so the E must increase. The result: greater amplitude and speed at BDC (all KE). Qualitatively this is intuitive. Pulling requires work which is added to the pendulum. What about changing the g?

Again increasing g increases the frequency and energy (work on the field added), so the E increases again intuitive ("sort of"). but what about the speed at BDC (all KE) should be greater, intuitive, no?

Here's my problem: The amplitude? greater? But the g is increased so the "work" to reach a given amplitude is also increased. So what's the amplitude??

bc physics challenged


p.s. note if it's a clock pendulum and the g stops changing the equilibrium energy will be as before the g change, no? (Assume drive is independent of the amplitude.)