QUES: 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.
Do you have any questions?
MY QUESTION: How does a heavy object have more friction?

QUES: Clarifying the Record The defense of U.S. airspace on 9/11 was not conducted in accord with preexisting training and protocols. It was improvised by civilians who had never handled a hijacked aircraft that attempted to disappear, and by a military unprepared for the transformation of commercial aircraft into weapons of mass destruction. As it turned out, the NEADS air defenders had nine minutes' notice on the first hijacked plane, no advance notice on the second, no advance notice on the third, and no advance notice on the fourth. We do not believe that the true picture of that morning reflects discredit on the operational personnel at NEADS or FAA facilities. NEADS commanders and officers actively sought out information, and made the best judgments they could on the basis of what they knew. Individual FAA controllers, facility managers, and Command Center managers thought outside the box in recommending a nationwide alert, in ground-stopping local traffic, and, ultimately, in deciding to land all aircraft and executing that unprecedented order flawlessly. More than the actual events, inaccurate government accounts of those events made it appear that the military was notified in time to respond to two of the hijackings, raising questions about the adequacy of the response. Those accounts had the effect of deflecting questions about the military's capacity to obtain timely and accurate information from its own sources. In addition, they overstated the FAA's ability to provide the military with timely and useful information that morning. In public testimony before this Commission in May 2003, NORAD officials stated that at 9:16, NEADS received hijack notification of United 93 from the FAA. This statement was incorrect. There was no hijack to report at 9:16. United 93 was proceeding normally at that time. In this same public testimony, NORAD officials stated that at 9:24, NEADS received notification of the hijacking of American 77. This statement was also incorrect. The notice NEADS received at 9:24 was that American 11 had not hit the World Trade Center and was heading for Washington, D.C. In their testimony and in other public accounts, NORAD officials also stated that the Langley fighters were scrambled to respond to the notifications about American 77,178 United 93, or both. These statements were incorrect as well. The fighters were scrambled because of the report that American 11 was heading south, as is clear not just from taped conversations at NEADS but also from taped conversations at FAA centers; contemporaneous logs compiled at NEADS, Continental Region headquarters, and NORAD; and other records.
Do you have any questions?
MY QUESTION: Who needed to clarify the record of the U.S. defense of 9/11?

QUES: Federal health authorities Monday added 58 types of cancer to the list of covered illnesses for people who were exposed to toxins at the site of the World Trade Center in the aftermath of the September 11 attacks. The addition finalizes a recommendation from Dr. John Howard, administrator of the World Trade Center Health Program. Howard proposed in June that the program accept the recommendations of its Science/Technical Advisory Committee and add some cancers to the coverage list -- 14 categories in all. Firefighters responding to 9/11 at increased cancer risk The advisory committee review called for expanded "coverage for certain types of cancer resulting from exposure to toxins released at Ground Zero." "The publication of this final rule marks an important step in the effort to provide needed treatment and care to 9/11 responders and survivors through the WTC Health Program," Howard said in a statement Monday. The rule is expected to be published Wednesday in the Federal Register, and will take effect 30 days after its publication, Howard said. 9/11 detective dies after battle with lung cancer First responders, volunteers, survivors of the attacks and residents near the site who meet specific qualifications will be eligible for coverage, according to the World Trade Center Health Program. According to the proposed rule, an estimated 950 to 2,150 people would take advantage of the additional coverage. The estimated cost for the total cancer treatment ranges between $14.5 million and $33 million, the proposal said.
Do you have any questions?
MY QUESTION: Who's recommendation was finalized by an addition made to the list of covered illnesses for people who were exposed to toxins at the site of the World Trade Center during the 9/11 attacks?

QUES: Tuesday, September 11, 2001, dawned temperate and nearly cloudless in the eastern United States. Millions of men and women readied themselves for work. Some made their way to the Twin Towers, the signature structures of the World Trade Center complex in New York City. Others went to Arlington, Virginia, to the Pentagon. Across the Potomac River, the United States Congress was back in session. At the other end of Pennsylvania Avenue, people began to line up for a White House tour. In Sarasota, Florida, President George W. Bush went for an early morning run. For those heading to an airport, weather conditions could not have been better for a safe and pleasant journey. Among the travelers were Mohamed Atta and Abdul Aziz al Omari, who arrived at the airport in Portland, Maine. Boston: American 11 and United 175. Atta and Omari boarded a 6:00 A.M. flight from Portland to Boston's Logan International Airport. When he checked in for his flight to Boston, Atta was selected by a computerized prescreening system known as CAPPS (Computer Assisted Passenger Prescreening System), created to identify passengers who should be subject to special security measures. Under security rules in place at the time, the only consequence of Atta's selection by CAPPS was that his checked bags were held off the plane until it was confirmed that he had boarded the aircraft. This did not hinder Atta's plans. Atta and Omari arrived in Boston at 6:45. Seven minutes later, Atta apparently took a call from Marwan al Shehhi, a longtime colleague who was at another terminal at Logan Airport. They spoke for three minutes. It would be their final conversation.
Do you have any questions?
MY QUESTION:
What was the weather like when President George W. Bush went for his early morning run?