The Doppler effect - the shift in frequency/wavelength of a
sound source when there is relative motion between source &
observer - and a Sonic Boom - a conical region of compression that
forms around the sound source when its speed exceeds the speed of
sound in the medium of the source, and results in an observed
"boom" when part of the cone passes the observer's location - are
two interesting, common, as well as connected phenomena seen this
week....