From the record
Real cases, written from the published record. Predict first; the record and its sources come after.
1971 · Hadley Rille, the Moon
Mr. Galileo was correct
At the end of the Apollo 15 moonwalk, David Scott held up a geologic hammer in one hand and a falcon feather in the other, in front of the TV camera.
The hammer has a mass of about 1.32 kg; the feather about 0.03 kg. The Moon has no air.
He let go of both at the same moment. Which landed first?
What happened. They fell side by side and hit the dust together. Scott said, "…which proves that Mr. Galileo was correct in his findings."
Without air, everything falls the same way. Air is what made the feather float.
1340s · Paris and 1980 · Baltimore
The curved tube
In the 1340s Jean Buridan argued that a thrown stone carries an impetus, given by the hand, that keeps it moving until air and weight wear it down.
In 1980 three psychologists asked university students a simple question: a ball rolls fast through a spiral tube lying flat on a table, and comes out of the end.
Once the ball leaves the tube, what path does it follow (seen from above)?
What happened. Newton's first law says a straight line: nothing pushes it sideways once it leaves the tube. But a large share of the students drew a curve, as if the ball carried a curving "impetus" from the tube, even many who had studied physics.
What we don’t know. Buridan himself wrote mostly about straight-line motion; the curved-impetus idea was held by other medieval writers and, it turns out, by many of us.
Careful thinkers have reasoned this way for centuries. If you drew a curve a minute ago, you're in good company, and now you know the test.