I bought this book because of Mr. Kurtis's excellent teaching methods exemplified on his websites. However in using his book as a physics reference I come across the same mistaken reasoning that has plagued physics to this day; the idea that ALL `balls' fall to the Earth at the same time if dropped from the same height.
One can certainly understand Galileo's mistake in not accounting for the fact that the mass of any objects dropped is negligible as compared to the Earth, or the Moon for that matter. But why does the mistaken reasoning continue to this day? Could it be Einstein's logical fallacy of developing GR `assuming' this was the case? Science removed from metaphysics and logic should always be viewed with skepticism IMHO.
Let's do 2 experiments and compare the results. We'll do first one experiment, then the other one. We won't drop our `balls' to the Earth at the same time.
Take a ball with a mass of 1.8986×1027 kg [mass of Jupiter] and hold it 5 miles from its surface to the surface of the Earth. Calculate the time of fall, after the ball is released, such that the surface of the ball and the surface of the Earth make contact. Ignore any effects of atmosphere.
Now take a ball with a mass of 1 kg and hold it 5 miles from its surface to the surface of the Earth. Calculate the time of fall, after the ball is released, such that the surface of the ball and the surface of the Earth make contact. Ignore any effects of atmosphere.
Common Physics texts, Mr. Kurtus's book, and our most revered institutions such as NASA will tell you the Force of gravity is equal to:
Force = mass1 times mass2 divided by the radius distance between the cm of the objects all times G the gravitational constant. From the distance formula, distance = at2 and the time of fall is equal to the square root of 2d/a. The acceleration of gravity on the Earth a=9.8 m/s and the acceleration of gravity on Jupiter a=26 m/s. Clearly juxtaposing Jupiter and the Earth 5 miles apart from their surfaces means that Jupiter will fall (accelerate) towards the Earth at 9.8 m/s and Earth will fall (accelerate) towards Jupiter at 26 m/s.
Can this joint attraction of the two `masses', Earth and Jupiter, really be the same as the joint attraction of the Earth and a 1kg mass? Will Jupiter and the 1kg mass arrive at the surface of the Earth at the same time?
Thus the hypothesis that all masses fall to the Earth at the same time, regardless of their mass in proportion to the Earth is wrong. Does a spaceship orbiting Jupiter and a spaceship orbiting the Earth have the same orbit? The same velocity? The multiple uses of this accepted fiction nevertheless render its applications to be limited.
The Equivalence Principle is false.
Mr. Kurtus's book remains a good reference for the science of our times, but is destined to the fate of a yesteryear textbook on Ptolemy's cosmology.
