QUES: We do not know exactly how the hijackers gained access to the cockpit; FAA rules required that the doors remain closed and locked during flight. Ong speculated that they had "jammed their way" in. Perhaps the terrorists stabbed the flight attendants to get a cockpit key, to force one of them to open the cockpit door, or to lure the captain or first officer out of the cockpit. Or the flight attendants may just have been in their way. At the same time or shortly thereafter, Atta-the only terrorist on board trained to fly a jet-would have moved to the cockpit from his business-class seat, possibly accompanied by Omari. As this was happening, passenger Daniel Lewin, who was seated in the row just behind Atta and Omari, was stabbed by one of the hijackers-probably Satam al Suqami, who was seated directly behind Lewin. Lewin had served four years as an officer in the Israeli military. He may have made an attempt to stop the hijackers in front of him, not realizing that another was sitting behind him. The hijackers quickly gained control and sprayed Mace, pepper spray, or some other irritant in the first-class cabin, in order to force the passengers and flight attendants toward the rear of the plane. They claimed they had a bomb. About five minutes after the hijacking began, Betty Ong contacted the American Airlines Southeastern Reservations Office in Cary, North Carolina, via an AT&T airphone to report an emergency aboard the flight. This was the first of several occasions on 9/11 when flight attendants took action outside the scope of their training, which emphasized that in a hijacking, they were to communicate with the cockpit crew. The emergency call lasted approximately 25 minutes, as Ong calmly and professionally relayed information about events taking place aboard the airplane to authorities on the ground. At 8:19, Ong reported:"The cockpit is not answering, somebody's stabbed in business class-and I think there's Mace-that we can't breathe-I don't know, I think we're getting hijacked." She then told of the stabbings of the two flight attendants. At 8:21, one of the American employees receiving Ong's call in North Carolina, Nydia Gonzalez, alerted the American Airlines operations center in Fort Worth, Texas, reaching Craig Marquis, the manager on duty. Marquis soon realized this was an emergency and instructed the airline's dispatcher responsible for the flight to contact the cockpit. At 8:23, the dispatcher tried unsuccessfully to contact the aircraft.
Do you have any questions?
MY QUESTION: Who claimed they had a bomb?

QUES: In architecture Durer cites Vitruvius but elaborates his own classical designs and columns. In typography, Durer depicts the geometric construction of the Latin alphabet, relying on Italian precedent. However, his construction of the Gothic alphabet is based upon an entirely different modular system. The fourth book completes the progression of the first and second by moving to three-dimensional forms and the construction of polyhedra. Here Durer discusses the five Platonic solids, as well as seven Archimedean semi-regular solids, as well as several of his own invention. In all these, Durer shows the objects as nets. Finally, Durer discusses the Delian Problem and moves on to the 'construzione legittima', a method of depicting a cube in two dimensions through linear perspective. It was in Bologna that Durer was taught (possibly by Luca Pacioli or Bramante) the principles of linear perspective, and evidently became familiar with the 'costruzione legittima' in a written description of these principles found only, at this time, in the unpublished treatise of Piero della Francesca. He was also familiar with the 'abbreviated construction' as described by Alberti and the geometrical construction of shadows, a technique of Leonardo da Vinci. Although Durer made no innovations in these areas, he is notable as the first Northern European to treat matters of visual representation in a scientific way, and with understanding of Euclidean principles. In addition to these geometrical constructions, Durer discusses in this last book of Underweysung der Messung an assortment of mechanisms for drawing in perspective from models and provides woodcut illustrations of these methods that are often reproduced in discussions of perspective.
Do you have any questions?
MY QUESTION: In which book does Durer show the understanding of Euclidean principles?

QUES: Take a look at this train in Figure 1.11. It looks very futuristic. What do you notice about it? Did you notice that the train has no wheels? How can a train have no wheels? It doesn't need wheels. It actually floats, or levitates, just above the track. Magnets enable the train to do this. This is not a normal train. This is a maglev train. The word maglev stands for magnetic levitation. Because it has no wheels, there is no friction. Some magnets hold the train up. Other magnets are used to move the train forward. This train can go very fast. It can reach speeds up to 480 kilometers (300 miles) per hour! Magnets are pretty cool. What exactly is a magnet? How is it able to exert such force?
Do you have any questions?
MY QUESTION: What do you notice about figure 1.11?

QUES: Tropical climates are found around the equator. These climates have warm temperatures year round. Tropical climates may be very wet or wet and dry. Tropical wet climates occur at or very near the equator. They have high rainfall year round. Tropical rainforests grow in this type of climate. Tropical wet and dry climates also occur near the equator. They receive less rainfall. Most of the rain falls in a single season. The rest of the year is dry. Few trees can withstand the long dry season. The main plants are grasses. Dry climates receive very little rainfall. They also have high rates of evaporation. This makes them even drier. Deserts can get less than 25 centimeters of rain per year. Thats less than 10 inches per year. How much rain do you get at your house?
Do you have any questions?
MY QUESTION:
Why do tropical climates have warm weather?