Sinusoidal curves in everyday life

Harmonic and sinusoidal curves are everywhere in everyday life. One example is the classic ferris wheel example. A friend and you are on the on the ferris wheel and at time = 0 you are at the top and so on. This is the classic example. Every teacher uses it because it works. What I want to talk about isn't so much a "classic example" as one that I thought about and thought would work. Cars. As many of you know, I've got the car fever. I'm a motorhead and proud of it! Well one thing I noticed about cars is the ever changing color pallet and style of the car. Long ago all the cars were the same boring color: the color of the metal. One day someone painted the metal a cool color to be different. Soon everyone wanted to be different so they had different colored cars. As more and more of the different color cars were driven, people started wanting a more natural color for their car such as brown, black, white, and Navy blue. As these colors started coming back, the more odd colors such as orange and red and light blue started to fade. Any student or teacher that knows of harmonic modeling, knows that this is the start of a sinusoidal curve. The range of the graph is the amount of cars that have the cool colors vs the neutral colors and how many cars there are. The range is always increasing because there are new cars being made every year. The period of the graph would be a few years, depending on the data. As of right now, the cool colors such as orange and yellow are starting to fade and the neutral colors are starting to return. A sinusoidal curve can also be used to model the style of cars. The period of this graph would be not one year or even two years, but closer to 20 or so years. The car styles go from sporty then to boxy and somewhat ugly and back to sporty because boxy and ugly isn't selling. This sinusoidal curve has the same idea. As the boxy cars go out of style, the sporty cars become in style and then the curve goes to the sporty side. There are people in the car industry who do this to make the cars that the people want and so that people buy their cars and not the cars of other car brands. These curves really help business of all the car companies of the world.