If we have a driven damped harmonic oscillator:
$$
\frac{d^2x}{dt^2}+\gamma\frac{dx}{dt}+\omega^2_0x=\frac{F}{m} e^{i\omega t}
$$
amplitude resonant frequency occurs at:
$
\omega_R^2 = \omega^2_0x-\frac{\gamma^2}{2}
$
As energy of a spring is proportional to displacement squared, the maximum energy of the system is here.
But, velocity resonance occurs at:
$\omega=\omega_0$ as kinetic energy is proportional to velocity squared, the maximum energy of the system is here.
There is clearly a paradox here, I cannot understand how it can resonate at 2 different frequencies.
Best Answer
For simple harmonic motion the maximum speed $v_{\rm max}$ is related to the frequency $f$ and the amplitude $A$ as follows $v_{\rm max}=2\pi f A$.
So your two resonance graphs are showing how two different (but related) quantities, amplitude and maximum speed vary with the frequency of the driver.
For one you are looking for maximum $A$ and for the other maximum $(2\pi ) fA$.
Similarly when you compare the torque $\tau$ and the power $\tau 2 \pi f$ ($f$ is the frequency or engine speed) delivered by a motor car engine the two related quantities have different variations with regard to engine speed.
The peak torque which dictates the acceleration of a car occurs at a different frequency (engine speed, rps) from the peak power which determines the maximum speed of a car.