The chapter I summarized was about newtons law of gravity and its affect on Superman. I thought that this was appropriate because this is what we are focusing on in class. The chapter starts by asking the question how can Superman just leap to the top of a building. Then comes in the physics. It takes into account Superman's mass, the distance he is from the Earth, and the universal pull of gravity. It concludes to say that while on earth his weight not his mass is about 220 pounds. They do this by taking his mass and multiplying it by Earth's gravitational pull. They discover that the acceleration due to gravity which is the equation (G x Mass of the Earth)/ Radius of the earth squared. They discover that his gravitation acceleration is 32 feet/ sec squared. They discover that in order for superman to make that leap he would have to be from a planet with 15 times the gravitational pull of Earth. It goes on to explain why the Moon revolves around the Earth and the Earth around the Sun. It explains this by saying, the Moon is falling around the Earth and that the Earths gravitational pull determined by the size of the Earth keeps the Moon in close. But the speed that the Moon is falling at keeps it from striking the Earth. It also goes on to say that the shape of the planet is determined by its size. If the planet or object is larger than about 300 miles then is gravitational pull forms it into a sphere. Also a shout out to the movie Armageddon, if the asteroid was as big as they say it was then it would be in the shape of a sphere not the shape showed in the movie. They continue to break down the reason that Krypton's gravitational acceleration is 15 times stronger than Earths. In order for this to be true, Krypton must be 15 times larger than Earth or the same size as earth but 15 times denser. Due to the laws of gravity for earth that they would assume were true on krypton, it would be impossible for Krypton to be 15 times dense as earth. They explain this by saying that the density is equivalent to how close the atoms are packed together. The closeness that the atoms would have to achieve to produce a density of 15 times the Earths is nearly impossible due to quantum mechanics. But if it were possible some how it still geology wise be near impossible. The Earth is the most dense planet in the universe at 5 grams/ cubic cm. So even if the planet was made of uranium it would only have a density of about 19 grams/cubic cm. Which is less than four times the density of Earth. So to acquire 15 times the density of earth it would have to have the density of 75 grams/cubic cm. There is no natural substance that has that kind of density. But in defense there have been exotic materials found in outer space, although none to my knowledge are dense enough there still is a possibility. They go on to say that it is just as unlikely that the planet could be 15 times larger than Earth. Jupiter which is 11 times the size of the Earth, which is pretty close to our magic number of 15 times the size of Earth. The problem is that it is so large that the atoms are all spread out and that it's really just a big ball of gas. Making it impossible to even walk on much less build an entire civilization on. But there is one exception, If the core of Krypton comprised of neutron star material which is the material of a star after it has exploded, with a radius of about 600 meters. It would have the density that of 15 times that of Earth. But with this the planet because of its extreme density would not be able to distribute mater. There would be volcanic eruptions and large tectonic shifts. This would essentially cause the planet to fall apart. Also this would persuade mothers to put their infant in a rocket and send him to a far away planet called Earth. Where the child would discover his abilities and save the world day after day from evil villains.