This weekend was exhausting and I drove A LOT. Saturday I drove from Kaneohe to Moanalua High School (for the ACT), then to Hawaii Kai, then to Hawaii Loa Ridge, then to Ward, then to school, and then finally back to Kaneohe. Then Sunday I drove from Kaneohe, to Hawaii Kai (for a community service project this time) to Kailua, then back to Kaneohe. Plus there was traffic. I was probably in the car for about 4 hours. So being on the road for so long I was able to witness many examples of the doppler effect with many ambulences speeding by, and fast, noisy cars and motorcycles driving past me. The Doppler Effect is a change in the frequency of a wave due to motion of the source and listener. As the vehicles approached me, the frequency of their sound waves were higher because the waves arrive closer together. However once the vehicle passed me and drove away, the frequency was lower because the sound waves weren't reaching me as fast. Although the frequency of the sound emitted by the source actually stayed constant, me (the listener) perceived the frequency to be changing due to the motion of both me and the source.