The magnet fell quite freely through an aluminum pipe of somewhat larger diameter, however. The definitive experiment would require a solid copper pipe, and an Al pipe with thick walls. There was subsequent discussion of the book Conceptual Physics by Paul Hewitt . It was suggest that the book would be appealing to students who understand the concepts of mathematics, but who do not like quantitative problems. Porter Johnson suggested that the best evidence might come from a study of the trajectory of the golf ball, which should be truly parabolic on the moon, with no possibilities of a slice, no effect of back-spin, etc.
Air resistance is very important for the flight of a golf ball on earth, in contrast to on the moon.
She laid out a distance of 2 meters with meter sticks. When she went North , the distance read 1.985 m, whereas going South it read 2.010 m. Similarly, going East she obtained 2.02 m, versus 1.985 m going West . The answer seems to relate to an asymmetry in the nap of the carpet. Porter Johnson did a demonstration of using the points on a compass to specify directions using a real compass to interested parties after the class.