A Simple Demonstration of Space/Time Relativity

[Vince]

This is so simple, I’m sure others have thought of it. So, it’s only relatively original.  All you need is a piece of paper, some scissors, and a pen or pencil.

1. Cut the paper into a perfect circle. You can do this easily by folding the paper and cutting it in half a circle.
2. Find the exact center of the circle and place a dot there.
3. Two inches from the center place another dot.
4. In line with the first two dots, place another dot four inches from the center.
Distances don’t matter, but to make things simple and ease your observation, keep your dots in one line along one radius from the center to the circumference of your circle.

Now rotate your circle using the center dot as your axis. Note, this is one solid piece of paper so it’s all moving at the same speed. Yet while the center dot stays in place, the second dot my move an inch and the third dot may move two inches.

How can this be? how can objects moving at the same speed, for the same duration of time, move different distances?

Once you  grasp the basic concept you can experiment with different distances using triangulation and epicurean mathematics to make calculations and satisfy your own curiosity.

As others have said when things are spinning the speed is measured in radians/sec not a distance per second.  So all points on the disk have the same radial speed.  As the points go further out from the center they have to travel a longer distance to keep up but they are still going the same radians/second (radial speed) as every other point.