Chapter 9 Review - Physics: Fill & Download for Free

I’m not familiar with the details of Luis Alvarez’s interactions with the scientists who refused to accept the theory that he proposed, in collaboration with his geologist son Walter, that the Cretaceous–Paleogene extinction event was caused by an asteroid impact. But I’m concerned that the other answers currently offered to this question do not reflect that fact that, at the present time, the overwhelming consensus is that Alvarez was right, especially in light of the accumulated evidence that the Chicxulub crater in the Gulf of Mexico was made by that dinosaur-killing asteroid (known in this context as the “Chicxulub impactor”).Let me document that point with this summary of an article published in late 2016 in the journal Science, where the Chicxulub crater is described, without any qualification, as the remnant “of an asteroid impact off the Yucatán Peninsula in Mexico that killed off the dinosaurs 66 million years ago”. Already in 2010 Science had published this review article, signed by 41 authors and which concludes that “the Chicxulub impact triggered the mass extinction.” This webpage from the Universities Space Research Association’s (USRA) Lunar and Planetary Institute characterizes as the “rock solid” “international consensus” what’s still misleadingly called the “Alvarez hypothesis”.Of course, when Alvarez was arguing his case in the 1980s he didn’t have the geological evidence from Chicxulub. I’m not personally qualified to judge the merits of the evidence that was being debated back then, but I note the quote that Martin Pollard has already highlighted here, from chapter 9 of the book in the question’s link, written in 1995:The partisans of the asteroid theory soon won over the community of geophysicists, geochemists, and astrophysicists — those who were the most readily inclined to deal with mathematical, physical, or chemical concepts using quantitative models. Geologists and paleontologists, who prefer to be closer to field observation, held back for a longer time.This, coupled to the fact that we now know that Alvarez was right, suggests to me that there probably was something to Alvarez’s impolitic characterization of his critics as “not very good scientists” and “more like stamp collectors.”

According to me, physics of class 11 is simple but comparing to the physics we have studied in 10th standard, it is way too tough. I may give you portions which I found tough.Commenting about the first book (we have two books for class 11 physics) I think it consist of comparatively easier chapters. A lot of students and myself found the chapter 7 (System of rotational motion) a little bit tough and lengthy. But once you catch the concept, it will be easier. Gravitation (chapter 8) is easy but it consists of derivations which you can easily forget.Second books begin with chapter 9 (Mechanical properties of solids) and Chapter 10 (Mechanical properties of Fluids) which are easy chapters. Fluids contain a lot of derivations, so be careful with that. Thermodynamics, kinetic theory and thermal properties of matter are medium difficulty level chapters which you can surely master. Then comes linked oscillations and waves chapters, they are really easy too. Maybe some may find oscillations tough. I may advice you to study oscillations first and then do waves. This is a must. Don't mess that order.And also, one thing I forgot to write, I suggest you to complete Chapter 5 (Laws of motion) before studying Chapter 7 (Rotation) as there involves a lot of concepts such as free body diagrams which will be involved in rotational mechanics.That's all, if you read this review, according to me, physics of 11th standard is easy.Thanks :))

Ryan Zwilling's answer is very good so I don't have a lot to add. Here are some more references. This is the definitive summary of the evidence up to 2007, with lots of references:Intergovernmental Panel on Climate Change, Climate Change 2007: Working Group I: The Physical Science Basis, Chapter 9: Understanding and Attributing Climate Change.An updated version will come out soon. In the meantime, a nice review of recent work is here:Skeptical Science, A Comprehensive Review of the Causes of Global Warming.One good thing about some of this new work is that it estimates the amount of climate change that could be due to variations in the brightness of the Sun, and other factors. Some of these studies estimate that more than 100% of climate changes is man-made. In other words, they estimate that natural variations are reducing the amount of global warming.