Understanding frequency and dynamics

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1. Apr 2, 2015

rrdrr8556

Can someone please explain intuitively how the terms “frequency” and “dynamics” are related ? I understand the concept of each of these two individually, but I am having some difficulty visualizing what high-frequency dynamics mean.

I understand the concept of how time and frequency domains work using the Fourier transforms. Essentially, in time domain all signals can be considered to be a sequence of sine waves of different frequencies added together. Using FT, the individual components can be seen separately.

I also understand that dynamics refers to an ordinary differential equation of how a system moves, given an external force. I understand this essentially in time domain, where typically a second order system is solved to get the time history of the position, velocity and acceleration.

However, I am completely stumped trying to understand how dynamics relates to frequency. What does the term “high-frequency” dynamics mean? I mean I can compute the equivalent transfer function and look at the damping ratio but how does all this relate to frequency response?

2. Apr 4, 2015

Puma

I couldn't find any formula for dynamics. I would guess it relates to the rate of change of amplitude?

3. Apr 4, 2015

Staff: Mentor

Frequency is well defined in physics. Dynamics less so. Dynamic can simply mean not static. I would t get too hung up on the meaning of dynamics

I expect that high frequency dynamics refers to short durations. When lightning hits a power line, the dynamics of what happens in the first microsecond can be analyzed separately than what happens in the first milliseconds, which an be separated from what happens in the first second. You simplify your analysis by pruning away effects that are too fast or too slow to be of interest.