Homage to Rube Goldberg

It all starts with a single ball -- and, of course, a lot of potential energy

Ladies and gentlemen, for your consideration — a real-life Rube Goldberg machine! As you may or may not be aware, Rube Goldberg was an early 20th century cartoonist (and engineer). His cartoons depicted imaginary machines capable of performing ordinary tasks in an extremely complicated way. Here in these modern times, we see the Rube Goldberg legacy in the children’s game called “Mousetrap.” In the educational arena, the building of Rube Goldberg machines has become a popular project in high school and college physics classes, and for hobbyists dabbling in this whimsical genre. Why? Because these contraptions beautifully illustrate a number of fundamental physics principles.

Now, the astonishing machine in this video looks a little bit too good to be true, and we suspect that those cuts in the video probably reflect some tinkering to make this look like a continuous and fully functioning “RGM.” Might there have been a few restarts during the filming? Probably. Nevertheless it’s really fun to watch this one. It’s pretty spectacular, creative, funny, and generally cool.

As far as the physics is concerned, although a successful Rube Goldberg machine involves multiple concepts, the core principle — the thing that really drives the action — is the principle of conservation of energy. Basically a Rube Goldberg machine is stacked with stored potential energy just waiting to be converted into other forms of energy. Usually, as in the video, much of the energy is stored in the form of gravitational potential energy.

For example, a ball placed near the top of a ramp has gravitational potential energy relative to the bottom. When the ball is released, the potential energy is then converted into kinetic energy as the ball falls and picks up speed. This kinetic energy can then do work on the next device along the line, triggering another transformation, etc. Notice in the video how the machine descends into the basement, thus optimizing the available gravitational potential energy.

Of course, potential energy can also be stored in chemical bonds, in elastic materials, and so forth; and in addition to kinetic energy, this potential energy can be converted into things like electric current and thermal energy. Look for examples of these types of transformations in the video!

Adam Weiner is the author of Don’t Try This at Home! The Physics of Hollywood Movies.