Physics · MU Sofia

8. Mechanical oscillations and waves Basic parameters

Introduces mechanical oscillations and waves as energy transfer through a medium via oscillating matter, defining period, frequency and wavelength and how they relate to wave speed. Gives the harmonic oscillator displacement equation with its terms, the wave speed expressions for solids and gases, and the propagation equation. Ends by distinguishing transverse waves from longitudinal waves by particle displacement direction, with sound given as an example.

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

Topic 9 of 42 in the MU Sofia syllabus for Physics (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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