Physics » G. Waves and Optics » G.2. Mechanical Waves

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Two Types of Mechanical Waves

• Overview
• Identifying examples and properties of transverse waves
• Identifying examples and properties of longitudinal waves

Speed of Mechanical Waves

• Overview
• Recognizing that the speed of mechanical waves depends on the medium
• Recognizing that mechanical waves generally travel the fastest in solids, then liquids, then gases
• Recognizing that the speed of mechanical waves depends on the temperature of the medium
• Identifying examples and characteristics of refraction in terms of changes in speed, frequency, and wavelength
• Determining the wave speed on a stretched string using the equation v = √ (F_t/μ) where μ = m/L

Characteristics of Sound Waves

• Overview
• Recognizing that frequency determines pitch
• Recognizing that amplitude determines loudness
• Identifying regions of compressions and rarefactions for sound waves
• Measuring the intensity of a spherical sound wave using the equation I = P/ (4πr²)
• Comparing the relative intensities of two sound waves based on factors of 10 for every 10 dB
• Measuring the relative intensity of a sound wave using the equation β = 10log (I / I₀)

Doppler Effect for Mechanical Waves

• Overview
• Recognizing the apparent change in frequency of a sound source moving away from an observer
• Recognizing the apparent change in frequency of a sound source moving towards an observer
• Recognizing the apparent change in wavelength of a sound source moving away from an observer
• Recognizing the apparent change in wavelength of a sound source moving towards an observer
• Calculating the observed frequency for a sound source moving toward an observer using f = f_o
• Calculating the observed frequency for a sound source moving away from an observer using f = f_o

Reflection and Interference of Mechanical Waves in One-Dimension

• Identifying the correct reflected wave for waves on a stretched string with a fixed boundary
• Identifying the correct reflected wave for waves on a stretched string with a free boundary
• Identifying the correct resultant wave for destructive interference
• Identifying the correct resultant wave for constructive interference

Reflection and Diffraction of Mechanical Waves Two-Dimensions

• Overview
• Determining the angle of reflection for a reflected mechanical wave
• Recognizing examples of diffraction

Harmonics 1: Standing Waves in Vibrating Strings

• Overview
• Identifying and counting nodes in a standing wave
• Identifying and counting antinodes in a standing wave
• Determining harmonic (resonant) wavelengths using the equation λ_n = 2L/n or λ_n = λ₁/n
• Determining harmonic (resonant) frequencies using the equation f_n = nv / 2L or f_n­ =nf₁

Harmonics 2: Standing Waves in a Closed Air Column

• Overview
• Determining the length of a tube based on the standing wave frequency or wavelength
• Determining harmonic (resonant) wavelengths using the equation λ_n = 4L/n or λ_n = λ₁/n for any odd integer n
• Determining harmonic (resonant) frequencies using the equation f_n = nv / 4L or f_n­ = nf₁ for any odd integer n

Harmonics 3: Standing Waves in an Open Air Column

• Overview
• Determining the length of a tube based on the standing wave frequency or wavelength
• Determining harmonic (resonant) wavelengths using the equation λ_n = 2L/n or λ_n = λ₁/n for any integer n
• Determining harmonic (resonant) frequencies using the equation f_n = nv / 2L or f_n­ = nf₁ for any integer n