Sound waves are longitudinal, sinusoidal plane waves that are perceptible by humans from about 20 Hz to 20,000 Hz. These waves can be characterized by frequency, wavelength, wavenumber, amplitude, sound pressure, sound intensity, speed, and direction.
"SONIC BOOM" sounds familiar, but what exactly is it? A sonic boom is the point where the shock waves that are created travel faster than the speed of sound "mach 1". Sonic booms occur when there is a large amount of energy at one time, resulting in a sound that resembles an explosion! This is common in planes when they are traveling very fast!!
Lastly, the doppler effect is the change in frequency of a wave for an observer moving relative to its source. For example, when a car is passing you and it's beeping it's horn, the frequency is higher when it is approaching and passing you and lower when it is receding. As the source of the wave (the car) is moving closer to the observer, the wave crests are emitting from a position closer to you, therefore, increasing the frequency. On the other hand, when the wave is moving away from the observer, each wave is emitted from a position further from you, therefore, the frequency is decreased.
It's kind of hard to catch the doppler effect or sonic boom on camera! Nevertheless, here's an example! If someone was standing on the side of this road, as I approached them (traveling at 60+ mph on the highway) they would hear a high pitched, high frequency noise. Just after I passed them, they would hear a low frequency, low pitched noise. Next time you're walking on the side of the road, stop and listen for the doppler effect!
No comments:
Post a Comment