To understand the terms in the Doppler shift formula. The Doppler shift formula gives the frequency fL at which a listener L hears the sound emitted by a source S at frequency fS: fL=fSv+vLv+vS, where v is the speed of sound in the medium, vL is the velocity of the listener, and vS is the velocity of source. Part A The velocity of the source is positive if the source is . Note that this equation may not use the sign convention you are accustomed to. Think about the physical situation before answering. View Available Hint(s)