Physics of Hearing Doppler effect and sonic boom

The whine of a motorclye's engine is changed when it passes by a stationary person compared to someone who is moving in the opposite direction. The same thing happens when someone is closer or farther away from the motorcycle The shift in the engines pitch is higher the closer you are and lower the farther you are. This effect is known as the Doppler effect.

The Doppler shift is caused by how close or how far away you are to a stationary object. A car that is speeding by two pedestrians on opposite sides will have the same wave lengths. Meanwhile a car going the same speed would have different sized wavelengths depending on how close one pedestrian is from the other. The Doppler shift is a sensory illusion.

A Sonic Boom to bow wake is where the jet plane approaches or exceeds the sound barrier. A bow wake is created when the sound wave is traveling slightly faster than the propagation speed. Planes are heard before they are seen because they are traveling so fast.


wave length and frequency are related by Vw = fλ, where Vw is fixed speed of sound

frequency =Fobs

Fobs=Fs(Vw/ Vw+-Vs)

Fs is the frequency of the source, Vs is the speed of the source along a line joining the source and observer


Created with images by skeeze - "military jet flight flying" • Advait Berde - "untitled image" • paulbr75 - "car engine engine motor" • skeeze - "sound barrier broken navy jet"

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