Problem 3
A sound source of frequency moves directly toward a stationary listener at speed , where is the speed of sound in air. Find the observed frequency. Assume the string, pulley, electrical source, or optical apparatus is ideal as stated, and neglect any effect not specified. State a clear sign convention, identify the physical Keep one model and sign convention throughout. Reuse each intermediate result with the same convention, then check that the answer has the required physical dimensions. (a) Set up the physical relation. (b) Find an intermediate quantity. (c) Obtain the answer and check its conditions and units.
problems.proof.stepOf
problems.proof.analysis
The listener receives crests at speed , so arrival interval equals their spacing divided by sound speed. This is consistent with the stated model and the chosen sign convention.