5. Seemingly Impossible

Please refer to the following link to learn how to make your own square gears: https://drive.google.com/file/d/0BzUNlD3nbDosaTc4Qll3VXVkdG8/view?usp=sharing

• For discussions of related issues, please google "brachistochrone." We thank Ms. Laura Simko for bringing this term to our attention.

• This is also known as Galileo's paradox.

• Please refer to http://en.wikipedia.org/wiki/Magnetic_levitation for more information.