So you need a point, "zero point" as you really want the amplitude of the displacement as the conditions vary.
if you use a moving point to measure another moving point then you have to recalculate to get the simple displacement. As long as you get the equations of movement correct the result will be the same.
As a different example, we were ...
The common denominator in ICE and jet engines is probably imbalances of rotating masses.
ICE's have additional vibrations which are due to the firing of the different cylinders. The firing itself is a source of vibration. Depending on the condition of the engine and the fuel, the vibrations can intensify.
As additional source of vibration is the torque ...
From out-of-balance forces, caused by rotating and / or reciprocating masses.
Lots of published theory about this.
A quick google search gave the following:
As an equipment supplier, your responsibility is to avoid the resonance to occur between the equipment and its support, whether a skid or a frame that is to be supplied by you. It might be a problem down the road, but it's out of your hand to evaluate the fundamental frequency of an industrial building, which may have numerous vibratory equipment and ...
The major source of vibration especially in modern light floor structures with +25ft spans is the floor vibration under foot traffic.
foot traffic frequency is about 1.25 hertz. so most of the modern designs go for a natural frequency of 3 to 5 hertz for the floors. source
You want to design frequency outside of the resonance range with these floors.
Any point in a wave can be arbitrarily chosen as the reference and it wouldn't change the frequency and amplitude. but it would change the phase of the wave which is essential in complex analysis and tensor calculus.
y = A sin(B(x + C)) + D
A is th amplitude
Period = 2π/B
phase shift is C (positive is to the left)
vertical shift is D
it is interesting ...