by Dr. Ed Berry
Here’s the untold story behind my first scientific publication where you may find the story more interesting than the publication itself. It’s a story about how what we may think is so, is not so. It’s a story that attracted a lot of attention because it showed a logic error in simple physics made by Scientific American and by some authors of books on meteorology.
All high-school physics students can understand the physics involved but you may be surprised at the answer.
Here’s the problem.
Tie a small weight, say a fishing sinker, to a 3 ft length of kite string. Hold the end of the string in your hand and whirl the weight around in a circle. Then stick your finger in the path of the string, hold your hand steady, and let the string wind up around your finger.
Question: Does the speed of the weight increase as it winds closer to your finger?
According to Scientific American’s “The Amateur Scientist” of April 1960, the weight speeds up. Here’s what C. L. Stong wrote (pp 183-184):
The effect can be demonstrated by a primitive experiment that all of us have made at one time or another. Swing a small weight in a circular orbit at the end of a string, and let the string wind up on your finger as depicted in the accompanying illustration.