Which of the following is TRUE for vibration of a mechanical system

Dampingratio ($$\xi$$) is the ratioof thecritical damping to the actual damping

The damping can be obtained from the response of the system under forced vibration using logarithmic decrement method

For damped mechanical systems, the amplitude of vibration tends to become infinity when excitation frequency ($$\omega$$) reaches the system’s natural frequency ($$\omega_n$$)

Amplitude ratio and transmissibility of a vibration isolator is unity when the frequency of exciting force is $$\sqrt{2}$$ times the natural frequency