Direct quantitative measurements of Doppler effects for sound sources with gravitational acceleration

TL;DR

This paper presents simple laboratory experiments to quantitatively measure Doppler effects from accelerating sound sources using gravitational acceleration, suitable for educational settings and verified against fundamental physics principles.

Contribution

It introduces accessible experiments for measuring Doppler effects with accelerating sources, clarifying conditions for experimental measurability involving acceleration.

Findings

Doppler spectra analyzed for accelerating sources

Conditions for measurable Doppler effects clarified

Experiments validated against fundamental physics principles

Abstract

We explain simple laboratory experiments for making quantitative measurements of the Doppler effect from sources with acceleration. We analyze the spectra and clarify the conditions for the Doppler effect to be experimentally measurable, which turn out to be non-trivial when acceleration is involved. The experiments use sources with gravitational acceleration, in free fall and in motion as a pendulum, so that the results can be checked against fundamental physics principles. The experiments can be easily set up from ``off the shelf'' components only. The experiments are suitable for a wide range of students, including undergraduates not majoring in science or engineering.