Problem: Rough surfaces create more friction than smooth surfaces. Thats why cars have tires. Its also why we use rubber mats in areas that might get wet. In your bathtub, you may even use No-Slip tape. No-slip is another way of saying the items has a lot of friction. In Figure 1.9, the blades of the skates are very smooth. Thats why you cant slide across ice with shoes. The soles of your shoes are much rougher than skates. The rougher surface of shoes causes more friction and slows you down. Heavier objects also have more friction. A heavy object presses down with more force. The surfaces are held together more tightly. This makes the surfaces harder to slide past each other. Did you ever try to push something heavy across the floor? Heavy objects are much harder to push than light objects.

Question: "Why do we use rubber mats in areas that might get wet?"

Answer: "Because, Rough surfaces create more friction than smooth surfaces"
Answer: yes

Problem: As noted above, the 9/11 plotters spent somewhere between $400,000 and $500,000 to plan and conduct their attack. The available evidence indicates that the 19 operatives were funded by al Qaeda, either through wire transfers or cash provided by KSM, which they carried into the United States or deposited in foreign accounts and accessed from this country. Our investigation has uncovered no credible evidence that any person in the United States gave the hijackers substantial financial assistance. Similarly, we have seen no evidence that any foreign government-or foreign government official-supplied any funding. We have found no evidence that the Hamburg cell members (Atta, Shehhi, Jarrah, and Binalshibh) received funds from al Qaeda before late 1999. It appears they supported themselves. KSM, Binalshibh, and another plot facilitator, Mustafa al Hawsawi, each received money, in some cases perhaps as much as $10,000, to perform their roles in the plot. After the Hamburg recruits joined the 9/11 conspiracy, al Qaeda began giving them money. Our knowledge of the funding during this period, before the operatives entered the United States, remains murky. According to KSM, the Hamburg cell members each received $5,000 to pay for their return to Germany from Afghanistan after they had been selected to join the plot, and they received additional funds for travel from Germany to the United States. Financial transactions of the plotters are discussed in more detail in chapter 7. Requirements for a Successful Attack As some of the core operatives prepared to leave for the United States, al Qaeda's leaders could have reflected on what they needed to be able to do in order to organize and conduct a complex international terrorist operation to inflict catastrophic harm. We believe such a list of requirements would have included leaders able to evaluate, approve, and supervise the planning and direction of the operation; communications sufficient to enable planning and direction of the operatives and those who would be helping them; a personnel system that could recruit candidates, vet them, indoctrinate them, and give them necessary training; an intelligence effort to gather required information and form assessments of enemy strengths and weaknesses; the ability to move people; and the ability to raise and move the necessary money. The information we have presented about the development of the planes operation shows how, by the spring and summer of 2000, al Qaeda was able to meet these requirements. By late May 2000, two operatives assigned to the planes operation were already in the United States. Three of the four Hamburg cell members would soon arrive.

Question: "What time in 2000 does al Queada meet the requirements and what chapter can you find more details about financial transactions?"

Answer: "They met the requirements in late May and you can find more details in chapter 7"
Answer: no

Problem: Light rays strike a reflecting surface. They are then reflected back. You can predict the angle of the reflected light. Imagine a ball bouncing off a surface. Light can do the same thing. That is, assuming the surface is shiny. So how do you know where light will go after it strikes a shiny surface? It depends on how the light initially strikes the shiny object. Light does not always go straight toward a surface. Therefore, not all light bounces straight back. Sometimes, light can hit a surface at an angle. The angle at which it strikes the surface tells us how it will bounce off. While light is different to a ball, they react in a similar manner. Many sports rely on knowledge of reflection. Pool players know a lot about reflection. They take great care when they strike the pool ball. They need it to go to a certain place. They know the angle it will hit the side of the pool table.

Question: "What type of people know alot about reflection?"

Answer: "All the people in sports."
Answer:
no