# I On liquid oscillation excitation

#### Jiwon Han

(I'm new to the Forum, so if I violate the rules unknowingly, please do let me know)
So, during a recent research, I analyzed the frequency spectrum of our hand's oscillation while walking.
As it turns out, it contains distinct harmonic frequencies (around 1.8*n Hz), and the second among them corresponds to the natural frequency of the first antisymmetric mode (FAM) of liquid oscillation inside an upright cylindrical container with radius 8cm and height 9cm.

Would the following statement be physically sound?
"Since the driving force (exerted by the hand, and subsequently the cup) contains a frequency component that corresponds to the natural frequency of the FAM, resonance occurs for the FAM."

Or does resonance only occur when a purely sinusoidal signal is imposed upon the system?
Thanks.

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#### NascentOxygen

Mentor
(I'm new to the Forum, so if I violate the rules unknowingly, please do let me know)
So, during a recent research, I analyzed the frequency spectrum of our hand's oscillation while walking.
As it turns out, it contains distinct harmonic frequencies (around 1.8*n Hz), and the second among them corresponds to the natural frequency of the first antisymmetric mode (FAM) of liquid oscillation inside an upright cylindrical container with radius 8cm and height 9cm.

Would the following statement be physically sound?
"Since the driving force (exerted by the hand, and subsequently the cup) contains a frequency component that corresponds to the natural frequency of the FAM, resonance occurs for the FAM."

Or does resonance only occur when a purely sinusoidal signal is imposed upon the system?
Thanks.
Resonance can be observed with excitation that is periodic; the excitation need not be any particular wave shape. Your statement is valid. It might read better were it expressed: "... the periodic driving force ..." or "... the driving force function ...", or "... the motion of the hand (and consequently of the cup) ...".

#### Jiwon Han

Resonance can be observed with excitation that is periodic; the excitation need not be any particular wave shape. Your statement is valid. It might read better were it expressed: "... the periodic driving force ..." or "... the driving force function ...", or "... the motion of the hand (and consequently of the cup) ...".
thanks alot! :)

#### Maria Fitzpatrick

Mr. Jiwon Han, in your research you overlooked an important aspect which I feel would be eye opening once tested!

"On liquid oscillation excitation"

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