Modeling real-world phenomena with sine functions

(PRESS THE BUTTON AT THE BOTTOM OF THE WINDOW TO PLAY/PAUSE THE ANIMATION.)
Sine functions can be used to model many things, especially in relation to motion. Unchecking all the boxes except for the one you are looking at, look at each of the five examples here individually
and watch the motion of the system. Make sure you understand how the motion is related to the sine graph. After that, answer the following questions:
1) How is the motion similar and different in the four examples?
2) What are some other examples of systems that can be modeled using the sine function? (Try to think of at least three.)

Nathaniel Lovelady, 19 November 2013, Created with GeoGebra