Thanks for that article. It's an interesting story and very informative.https://www.researchgate.net/publication/257810349_Steinmetz_and_the_Concept_of_Phasor_A_Forgotten_Story
In the Steinmetz method, vector math in the complex plane, all of the values have a direct analogue in the observable physical reality.
Pendulum motion can be described by sinusoidal analysis like in LC circuits when the peak value of the pendulum's angle θ from the vertical is small so that sin(θ) ≊ θ. For larger motions elliptic functions instead of sinusoidal functions must be used for an accurate analysis.As you go from falling body, pendulum motion, spring and shock absorber, to inductance and capacitance, the math is the same.