What if two children push a swing at the same time? Would the swing go higher? Yes, together their force would be more. It is common for forces to be combined. Most objects on Earth have at least two forces acting on them. Do you know what one of them is? Of course, that force is gravity. How many forces do you have on you right now? Gravity pulls you down toward the center of Earth. Your legs exert a downward force. They hold you up against the pull of gravity. Consider the example in Figure 1.3. A book is resting on a table. Gravity pulls the book downward. It has a force of 20 newtons. At the same time, the table pushes the book upward. Its force is also 20 newtons. The table opposes the pull of gravity. 

Question: "How many forces does an object have?"

Response: "Two forces acting on it"

A: yes


Dick was enraged to see how contentedly the men bore the irksome confinement, the meager food, and harsh peremptoriness of the beardless boys set over them as guards.  Most of the prisoners passed the time in cards, playing for buttons, trinkets, or what not that formed their scanty possessions.  Dick learned that all the commissioned officers of the company with Wesley Boone had been wounded or killed in the charge near the stone bridge.  Wesley had been with the prisoners at first.  He had been struck on the head, and was in a raging fever when his father and sister came to the prison to take him away.  No one could tell where he was now, but Dick knew that he must be in the city, since there were no exchanges, the Confederates allowing no one to leave the lines except women with the dead, or those who came from the North on special permits.  Then he visited the provost headquarters, and was shown the complete list of names recorded in the books there; but Barney's was not among them.  At the Spottswood Hotel, the day after his coming, he met Elisha Boone, haggard, depressed, almost despairing.  Dick had no love for the hard-headed plutocrat, but he couldn't resist making himself known. 

Question: "Who were the men that bore the irksome confinement, the meager food, and harsh peremptoriness of the beardless boys set over them as guards?"

Response: "The guardsmen"

A: no


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. 

Question: "Where did Atta and Oari travel from, and where did they travel to?"

Response: "Florida to Boston"

A:
no