I've never understood the significance of the bode plot and the significance of synchrony. Now it makes so much more sense after seeing your experiment!
It is really hard to see the phase is -90 degrees. As you say, it looks like the phone bounces down (-180 degrees out of phase with your hand) when your hand goes up at resonance, but it is just plain hard to measure with your eyes, as it happens pretty fast. And as you indicate, the expected angle is -90 degrees. Nice illustration.
u can only increase the damping factor in the eqn till 1.4 or else damping constant becomes greater than 0.7 and there is no resonant peak so we see a steady fall of the bode magnitude plot
I still have a question, from the transferfunction I can calculate that the Phase for high frequencies is 180 degrees. But what does that mean pysically? Beacause I can imagine that at some point the phase will change again?
Assuming you don't have any time delays in your system, your maximum phase is 90 * (number of poles - number of zeroes). What that means is, in a linear model, higher frequencies get really delayed relative to incoming signal speed or frequency. If it changes again at really high frequencies, you have a high speed pole(s) or zero(s) that you haven't accounted for in your TF model. In a physical sense, what phase angle means is how much delay there is between an input signal at that frequency and its response. So if I have a -180 degree phase at a frequency of 100hz, it means that the high speed portions of my output signal are going to significantly lag behind the input above 100hz or its equivalent.
