The highest point of a wave is the crest. The lowest point is the trough. The vertical distance between a crest and a trough is the height of the wave. Wave height is also called amplitude. The horizontal distance between two crests is the wavelength. Both amplitude and wavelength are measures of wave size. The size of an ocean wave depends on how fast, over how great a distance, and how long the wind blows. The greater each of these factors is, the bigger a wave will be. Some of the biggest waves occur with hurricanes. A hurricane is a storm that forms over the ocean. Its winds may blow more than 150 miles per hour! The winds also travel over long distances and may last for many days.

What is the difference between wavelength and amplitude?

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.

From the time Atta and Omari boarded their flight in Portland, how long did it take them to reach Boston

(Financial Times) -- The increasing amount of personal information that can been gleaned by computer programs that track how people use Facebook has been revealed by an extensive academic study. Such programmes can discern undisclosed private information such as Facebook users' sexuality, drug-use habits and even whether their parents separated when they were young, according to the study by Cambridge university academics. In one of the biggest studies of its kind, scientists from the university's psychometrics team and a Microsoft-funded research centre analysed data from 58,000 Facebook users to predict traits and other information that were not provided in their profiles. The algorithms were 88 per cent accurate in predicting male sexual orientation, 95 per cent for race and 80 per cent for religion and political leanings. Personality types and emotional stability were also predicted with accuracy ranging from 62-75 per cent. Facebook declined to comment. The study highlights growing concerns about social networks and how data trails can be mined for sensitive information, even when people attempt to keep information about themselves private. Less than 5 per cent of users predicted to be gay, for example, were connected with explicitly gay groups. Michal Kosinksi, one of the report's authors, told the Financial Times that the university's techniques could easily be replicated by companies to infer personal attributes a person did not wish to share, such as sexual orientation or political views: "We used very simple and generic methods. Marketing companies and internet companies could spend much more time and resources, and hence get much higher accuracy than we did." Last week , the EU agreed to water down proposals for a radical overhaul of data privacy regulation. The move reflects governments' reluctance to impede internet businesses that might spur economic growth, and follows fierce lobbying from technology companies including Facebook and Google. Personal data has become big business. Wonga, the UK online lender, makes credit judgments within seconds based on thousands of pieces of information, including an applicant's Facebook profile. Tesco, the supermarket chain, this month started to use its customers' shopping histories to sell targeted online advertising. The report also revealed some unexpected correlations -- such as people who liked 'curly fries' having higher IQs, while those who like Facebook's "Sliding on Floors With Your Socks On" page were unlikely to use drugs.
According to the study by Cambridge Academics how accurately were they able to predict sexuality?