University Physics III · Mechanical Waves · 2.06
Sound as displacement and pressure
Longitudinal displacement, the pressure change equal to minus the bulk modulus times the displacement gradient and so a quarter cycle out of phase with the displacement, and speed as √(B/ρ), with the adiabatic ideal-gas result √(γ R T/M) for molar mass M, a continuum small-amplitude model that fails at shock amplitudes.
Course-map guide · not a complete lesson or simulationScope & orientation
What this subsection covers
Longitudinal displacement, the pressure change equal to minus the bulk modulus times the displacement gradient and so a quarter cycle out of phase with the displacement, and speed as √(B/ρ), with the adiabatic ideal-gas result √(γ R T/M) for molar mass M, a continuum small-amplitude mod…A strong response uses mode shapes and frequency spectra and states where the model stops being reliable.
Reasoning checklist
Evidence, assumptions and limits
Assumptions to state
State the system, observable, approximation, and conditions held fixed before using a model.
Evidence to collect
Can a single recorded pass-by recover both the emitted frequency and the source speed?
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Can a single recorded pass-by recover both the emitted frequency and the source speed? Useful evidence includes a time-frequency spectrogram, approach and recede frequencies, a two-unknown solution, an independent speed estimate, sampling-resolution limits, and uncertainty.
Limits to state
This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus.
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This GioPhysics course map is an adaptable learning sequence, not academic credit, accreditation, or a universal university syllabus. Third-semester content is the least standardised of the introductory sequence: departments place oscillations, waves, optics, and thermal physics differently, and the modern-physics units here are a bounded survey rather than a complete course in relativity, quantum mechanics, atomic, nuclear, or particle physics. Follow your institution's published scope, notation, laboratory programme, and assessment rules. A result should be checked against units, signs, limiting cases, and the conditions under which its model was derived.
Diagram & examples
Work the claim before choosing an equation
Interactive concept map
Follow the model from claim to evidence.
Model, evidence, and boundary
Which response about Sound as displacement and pressure is most defensible?
modelModel, evidence, and boundary turns the stated idea into a representation that can make a prediction.
Example questions
Try the reasoning before revealing the structure.
Which response about Sound as displacement and pressure is most defensible?
Quick check
Test the reasoning, not recall
Which response about Sound as displacement and pressure is most defensible?
Choose an answer to test the model.