Doppler Effect

So, while this isn't the best physics journal photo i've ever taken I think it clearly shows the true spark of realization of physics concepts in the real world (especially the bluriness and off-center-ness). So when walking around this weekend I experienced the Doppler Effect via this fire engine's movement and siren/horn. The Doppler Effect is the percieved change in frequency of a sound wave due to movement of the source of the sound or the one listening to it in relation to the source. As the fire engine sped toward me there was a build up of sound waves as it continued to get closer, resulting in a percieved higher pitch, yet the siren and horn are only single pitchs. Once the fire engine passed me and proceeded away from me, the listener, the sound waves reached me in longer intervals, which made me percieve a lower frequency, and thus lower pitch. If my iPhone somehow could have recorded the speed of the fire engine and the frequency of its siren while I took the picture and I could assume my speed, it would be possible to determine the frequency I percieved through the equation: fn=f((v+/-vL)/(v-/+vS)), where v is the speed of sound. This equation states that while the listener moves closer to the source or the source moves toward the listener the percieved frequency is higher, whereas when the listener is moving away from the source and vice versa the percieved frequency is lower.

Wave Motion Gun

Even though the title and the picture (the effect in the picture is based off the same concept as this journal though! [i think]) kind of suggest something, i'm not referring to illicit items, but the physics involved in my electric guitar. After learning about waves in our latest lesson, i began to notice the transverse waves created when i plucked my strings in stage band, which consequently produces longitudinal waves of sound that travel through the air and the floor and to our ears for interpretation. Sound and light are types of mechanical waves, and thus involve this force and said mediums to travel though. These waves cause particles to move back and forth, which allows the transfer of energy. Waves are measured in several different ways, all of which i found are important to my playing. The amplitude of a wave measures the height of the crest to the equilibrium and is percieved as the volume, as it increases so does the volume. The wavelength of a wave is the length of one cycle in meters, and as it decreases the frequency, or number of cycles per second, increases since they are inversely proportional. Thus, when i fret higher frets on the guitar, i am shortening the wavelength and thus increasing the frequency, which raises the pitch as we percieve it. Electric guitars have an added depth of physics, and their sound is made possible through electromagnetic induction, which uses the magnets in the pickups and the change in flux caused by plucking the strings, which disturbs the magnetic field to induce a current, which is sent to the amplifier, thru which the signal is magnified to produce "one big blast from your wave motion gun," although in a different context.