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 logarithmic decrement method is used to determine:
Answer: Damping ratio from free vibration decay
The logarithmic decrement δ = ln(x₁/x₂) is calculated from successive peak amplitudes in free vibration decay and directly gives the damping ratio.
Which theorem states that the rate of change of angular momentum equals the net torque?
Answer: Angular impulse-momentum theorem
The angular impulse-momentum theorem states ΣM = dH/dt, i.e., the net moment equals the time rate of change of angular momentum.
In vibration analysis, a node point is where:
Answer: Amplitude is zero in a mode shape
A node is a point in a vibrating structure where the amplitude of motion is zero for a particular mode shape.
The equation of motion for a viscously damped SDOF system under harmonic excitation is:
Answer: mẍ + cẋ + kx = F₀sin(ωt)
A single degree-of-freedom system with mass m, damping c, and stiffness k under harmonic forcing F₀sin(ωt) is governed by mẍ + cẋ + kx = F₀sin(ωt).
Critical speed of a rotating shaft is the speed at which:
Answer: Shaft speed equals natural frequency of lateral vibration
Critical speed occurs when the rotational speed equals the natural frequency of the shaft's lateral (bending) vibration, causing resonance and large deflections.
In projectile motion (neglecting air resistance), the horizontal acceleration is:
Answer: Zero
Without air resistance, no horizontal force acts on the projectile, so horizontal acceleration is zero and horizontal velocity remains constant throughout flight.