Dynamics and Vibrations Flashcards
6 cards from real BME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Dynamics and Vibrations flashcards as text
The transmissibility ratio in vibration isolation is less than 1 when the frequency ratio (r = ω/ωn) is:
Answer: r > √2
Vibration isolation is effective (transmissibility < 1) only when the excitation frequency exceeds √2 times the natural frequency of the isolator.
For a rotating unbalance, the centrifugal force causing vibration is proportional to:
Answer: Unbalance mass × eccentricity × ω²
The centrifugal force from a rotating unbalance is F = meω², where m is unbalance mass, e is eccentricity, and ω is angular speed.
The work-energy theorem states that the net work done on a particle equals:
Answer: Change in kinetic energy
The work-energy theorem states that the net work done equals the change in kinetic energy: W_net = ΔKE = ½mv₂² - ½mv₁².
A Fourier series is used in vibration analysis to:
Answer: Decompose periodic excitation into harmonic components
A periodic forcing function can be decomposed into sinusoidal harmonics using Fourier series, allowing response to each harmonic to be analyzed separately.
In a two-degree-of-freedom system, the number of natural frequencies equals:
Answer: 2
A system with n degrees of freedom has exactly n natural frequencies (and n corresponding mode shapes).
Gyroscopic effects in a rotating machine cause:
Answer: Precession of the spin axis when a torque is applied
A spinning body exhibits gyroscopic behavior where an applied moment causes precession — rotation of the spin axis perpendicular to the applied torque.