Physic Labs

Problem 3

A stationary sound source emits frequency f; an observer approaches at speed u in a medium where sound speed is c (u<c). Find heard frequency. Use the stated ideal model: quantities are constant or vary only as specified, with no extra drag, losses, or external influences. State a sign convention, keep units consistent, and use a classical approximation only where appropriate. (a) Set up the governing equation from a fundamental law. (b) Solve for the requested quantity under the stated conditions. (c) Check the result using a suitable limit, sign, or unit test, and report both the expression and its physical meaning.
fobs=vwave,obs/λsoundf_{\rm obs}=v_{\rm wave,obs}/\lambda_{\rm sound}
problems.proof.analysis

Solve the relation for the unknown while preserving algebraic signs and physical restrictions. Use any stated geometry or definition to express the result in the given data.