Galileo’s Inclined Plane

OU Inclined Plane

The Galileo Inclined Plane working replica that was expertly crafted by Ron Mitchell for the OU Galileo’s World exhibit back in 2015 is urgently in need of a new home. It is a beautiful work of art as well as a functioning precision scientific instrument. Here’s the flyer PDF from back in those days.

Galileo described his experiment with an inclined plane in Two New Sciences (1636). Unfortunately, he omitted many details about the plane itself. Sparing no cost, we asked master craftsman Ron Mitchell to design an inclined plane that would have delighted Galileo. It incorporates design details as described by Galileo, such as lining the ball channel with vellum. As an experienced musician, Galileo timed the duration of the balls’ descent to a 10th of a pulse beat, but we can use stopwatches if we prefer!

The greatest design challenge was to make the tilt of the beam adjustable, unlike the replica at the Museo Galileo (photo here). Ron’s brilliant solution was to employ one of Galileo’s favorite simple machines, the balance. In Ron’s elegant design, one may slide the massive beam to a desired height with a single hand. After careful research, Ron painstakingly constructed the plane according to the methods of Venetian shipbuilding.

Inclined plane in high position (compare with photo at top)

The balls ring bells as they roll down the track

The track is lined with vellum

The inclined plane works perfectly for 2-minute explanations of Galileo’s physics with visiting kids. Using two balls of the same diameter, one solid steel and one wooden, let them hold the balls and feel that the weight of the steel ball is many times heavier than the wooden ball. Have them place the two balls on the track at the elevated end, the steel ball in front of the wooden ball, and let go of the balls at the same time. Ask:

“Which ball will roll down the plane faster?”

If the steel ball is at least twice as heavy as the wooden ball, shouldn’t it reach the bottom at least twice as fast?

High school and undergraduate students can use the inclined plane to rigorously replicate Galileo’s experiments establishing the law of free fall. They can replicate Galileo’s experiments, first with the beam in its high position and then again in the low position, demonstrating that the angle of tilt makes no difference, and thus suggesting that the same results would obtain if the beam were raised to 90 degrees or the vertical position.

One of the most distinguished living Galileo scholars saw this inclined plane in person ten years ago. He was amazed at both its workmanship and its design. He said that all future attempts to replicate Galileo’s inclined plane should use it as their exemplar and be measured by their fidelity to it.

Two balls of unequal weight; will the heavy ball reach the bottom faster?

Students from Gordon Cooper experimenting with the inclined plane

It’s free! This is a remarkable instrument and a cultural heritage object. Nevertheless, we need to find a home for it by the end of the month — it can go to any educational entity or educator willing to come pick it up. The instrument is 26 feet and 7 inches in length. It is segmented and can be taken apart for transportation. The beams are heavy though, so a crew of stout young backs to help transport is needed. You’ll need a dedicated space. To fit it into a very wide spot in a hallway may unfortunately intrude upon fire marshal guidelines: plan for a minimum space 28 feet in length and 5 feet in width to accommodate it. We set up stanchions to keep people from tripping over the platform when not in use, and to keep folks from bumping their heads into the elevated end if someone left it raised in the high position. Perhaps you can get a sense of its dimensions from the photos above (click to expand).

Please share this link with anyone who might be interested.

Update: I’m happy to say that, as of Wednesday, August 13, 2025, this beautiful instrument was safely transported to Stillwater, Oklahoma, by Prof. Flera Rizatdinova, professor of physics at Oklahoma State University, where it will be treasured for years to come. We appreciate the work of Flera and other OSU personnel, including Dr. Dorinda Risenhoover, to make this superb cultural treasure available to students and visiting groups there. Contact Dr. Rizatdinova if you are interested in visiting OSU to see it.