Physics · MU Sofia

8. Mechanical oscillations and waves Basic parameters

Explains mechanical oscillations and waves as energy transfer through a medium via oscillating matter, defining period, frequency and wavelength and their relationship. It then covers sound as a mechanical wave, the harmonic oscillator equation with amplitude and phase, wave speed in solids and gases, and the propagation equation. It closes by distinguishing transverse from longitudinal waves by particle displacement direction.

Inside: 1 section · 4 labelled pictures · 9 flashcards · 2 min

Topic 9 of 42 in the MU Sofia syllabus for Physics (Dental Medicine, Year 1). The free AceMed note covers it in 1 section, about 296 words (2 min of reading), with 9 flashcards.

In this note

  1. Introduction

Introduction

Summary

  • Mechanical oscillations and waves involve the transfer of energy through a medium via matter's oscillation, characterized by basic parameters such as period (T), frequency (f), and wavelength (λ). Sound is a typical example, being an audible wave of pressure and displacement. The equation for harmonic oscillators and wave speed, including specific formulas for solids and fluids, highlights the relationship between these parameters. Mechanical waves can be either transverse, where particle displacement is perpendicular to the wave direction, or longitudinal, with displacement parallel to wave propagation.
  • Basic Parameters of Mechanical Oscillations and Waves:
  • Period (T): Time in seconds for a wave to complete one cycle of vibration.
  • Frequency (f): The number of cycles that pass a point per second, calculated as 1/T (Hz).
  • Wavelength (λ): The spatial period of the wave in meters, the distance over which the wave's shape repeats.
  • Mechanical Wave: Transfers energy through a medium, characterized by oscillations of matter.
  • Sound: A vibration that propagates as a typically audible mechanical wave of pressure and displacement.
  • Equation of Harmonic Oscillators:
  • Deflection time equation: y = A * sin(ωt + Φ₀), where:
  • y = deviation of the body from equilibrium,
  • A = amplitude (maximum displacement),
  • ω = 2πf (angular frequency),
  • Φ₀ = initial phase at t = 0.
  • Speed of Wave: c = f * λ
  • In solids, c = √(E/P); E = modulus of elasticity, P = density.
  • In gas
  • Equation of Mechanical Wave Propagation:
  • Velocity of the wave: v = λ/T = λf.
  • Mechanical propagation equation: Y = y(max) * sin[2π * (t/T - x/λ)].
  • Transverse and Longitudinal Waves:
  • Longitudinal Waves: Particle displacement is parallel to the direction of wave propagation, possible in both solids and fluids.
  • Transverse Waves: Particle displacement is perpendicular to the direction of wave propagation, typically observed in solids.

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