Harmonics AdvancedHardQuestion 31393
Question
A string vibrates simultaneously in 1st and 3rd harmonics with amplitudes A₁ and A₃. The waveform is:
- Ay = A₁ sin(πx/L)cos(ωt) + A₃ sin(3πx/L)cos(3ωt)Correct
- By = (A₁+A₃)sin(πx/L)cos(ωt)
- Cy = A₁A₃ sin(πx/L)cos(3ωt)
- Dy = A₁ sin(πx/L) + A₃ sin(3πx/L)
Correct answer
y = A₁ sin(πx/L)cos(ωt) + A₃ sin(3πx/L)cos(3ωt)
Explanation
Superposition of two modes: y = A₁ sin(πx/L)cos(ωt) + A₃ sin(3πx/L)cos(3ωt). Each mode has its own spatial pattern and temporal frequency.