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Dynamics and Vibrations Flashcards

7 cards from real EIT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Dynamics and Vibrations flashcards as text

  1. A spring-mass system has k = 400 N/m and m = 4 kg. What is the natural frequency in Hz?

    Answer: 1.59 Hz

    ω_n = √(k/m) = √100 = 10 rad/s; f_n = ω_n/(2π) ≈ 1.59 Hz.

  2. A simple pendulum has a length of 1 m. What is its period of oscillation? (g = 9.81 m/s²)

    Answer: 2.0 s

    T = 2π√(L/g) = 2π√(1/9.81) ≈ 2.01 s.

  3. Springs k₁ = 100 N/m and k₂ = 200 N/m are connected in series. What is the equivalent stiffness?

    Answer: 66.7 N/m

    1/k_eq = 1/100 + 1/200 = 3/200, so k_eq = 200/3 ≈ 66.7 N/m.

  4. Springs k₁ = 150 N/m and k₂ = 250 N/m are connected in parallel. What is the equivalent stiffness?

    Answer: 400 N/m

    Springs in parallel sum directly: k_eq = 150 + 250 = 400 N/m.

  5. What is the critical damping coefficient for a system with m = 2 kg and k = 200 N/m?

    Answer: 40 N·s/m

    c_cr = 2√(mk) = 2√(2 × 200) = 2√400 = 40 N·s/m.

  6. In a free vibration test, successive amplitudes are 5 mm and 2.5 mm. What is the logarithmic decrement?

    Answer: 0.693

    δ = ln(x₁/x₂) = ln(5/2.5) = ln(2) ≈ 0.693.

  7. An underdamped spring-mass system is given an initial displacement and released. Which response best describes the subsequent motion?

    Answer: Oscillation with exponentially decreasing amplitude

    An underdamped system oscillates at the damped natural frequency while amplitude decays exponentially.