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Monopoly is a board game published by Parker Brothers, a subsidiary of Hasbro. The game is named after the economic concept of monopoly, the domination of a market by a single entity. Monopoly is the most commercially-successful board game in United States history, with 485 million players worldwide. According to Hasbro, since Charles Darrow patented the game in 1935, approximately 750 million people have played the game, making it "the most played (commercial) board game in the world." The 1999 Guinness Book of Records cited Hasbro's previous statistic of 500 million people having played Monopoly. The mascot for the game is a monocle-wearing man, wearing morning dress, named Rich Uncle Pennybags (often referred to as Mr. Monopoly). Monopoly involves a portion of luck, with the roll of the dice determining whether a player gets to own key properties or lands on squares with high rents. Even the initial misfortune of going last is a significant disadvantage because one is more likely to land on property which has already been bought and therefore be forced to pay rent instead of having an opportunity to buy unowned property. There are, however, many strategic decisions which allow skilled players to win more often than the unskilled. Hasbro also offers a helpful strategy guide and different insights on their site. According to the laws of probability, seven is the most probable roll of two dice, with a probability of 1 in 6, whereas 2 and 12 are the least probable rolls, each with a probability of one in 36. For this reason, Park Place/Park Lane is one of the least landed-on squares as the square seven places behind it is Go to Jail One common criticism of Monopoly is that it has carefully defined yet almost unreachable termination conditions. Edward P. Parker, a former president of Parker Brothers, is quoted as saying, "We always felt that forty-five minutes was about the right length for a game, but Monopoly could go on for hours. Also, a game was supposed to have a definite end somewhere. In Monopoly you kept going around and around." However, the problem of time can be resolved by playing with a time limit and counting each player's net worth when the time is up. In fact, tournament play calls for a 90-minute time limit. [READ THE REST OF THIS ARTICLE]

A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel—the engine of the rocket—is usually a used plastic soft drink bottle. The water is forced out by a pressurized gas, typically compressed air. The term "aquajet" has been used in parts of Europe in place of the more common "water rocket" and in some places they are also referred to as "bottle rockets" (which can be confusing as this term refers to a firework in other places). The bottle is partly filled with water and sealed. The bottle is then pressurized with a gas, usually air compressed from a bicycle pump, air compressor, or cylinder up to 125 psi, but sometimes CO2 or nitrogen from a cylinder. Water and gas are used in combination, with the gas providing a means to store potential energy, as it is compressible, and the water increasing the mass fraction and providing greater momentum when ejected from the rocket's nozzle. Sometimes additives are combined with the water to enhance performance in different ways. For example: salt can be added to increase the density of the reaction mass resulting in a higher specific impulse. Soap is also sometimes used to create a dense foam in the rocket which lowers the density of the expelled reaction mass but increases the duration of thrust. It is speculated that foam acts as a compressible liquid and enhances the thrust when used with De Laval nozzles. The seal on the nozzle of the rocket is then released and rapid expulsion of water occurs at high speeds until the propellant has been used up and the air pressure inside the rocket drops to atmospheric pressure. There is a net force created on the rocket in accordance with Newton's third law. The expulsion of the water thus can cause the rocket to leap a considerable distance into the air. Typically launch pressures vary from 75 to 150 psi (500 to 1000 kPa). The higher the pressure, the larger the stored energy. The current record for greatest height achieved by a water and air propelled rocket is 2044 feet (623 meters), held by U.S. Water Rockets on June 14, 2007. This altitude was calculated by averaging two flights. The first flight achieved 2068 feet (630 meters) and the second 2020 feet (615.7 meters). The rocket also carried an onboard video camera on both flights. [READ THE REST OF THIS ARTICLE]

American Airlines Flight 191, from O'Hare International Airport in Chicago, Illinois, to Los Angeles International Airport, crashed during take-off on May 25, 1979 at approximately 15:04 CDT. The McDonnell Douglas DC-10-10 had 258 passengers and 13 crew on board. There were no survivors. Two persons on the ground were also killed. In terms of total fatalities it remains the deadliest single airliner accident on U.S. soil. At 14:50 CDT, N110AA was cleared to taxi to runway 32R (Right) and at 15:02, the flight was cleared for takeoff and began its roll down the runway. Takeoff was normal until air traffic controller Ed Rucker witnessed the number one engine (left wing) separate from the aircraft. The engine flipped over over the wing and fell onto the runway. The aircraft continued in a normal climb momentarily to around 350 feet AGL, as leaking fuel and hydraulic fluid spewing a vapor trail. Such an incident is theoretically survivable in a DC-10; the shift in center of gravity and mean aerodynamic chord were within tolerances, and the aircraft could have landed safely if the engine loss had not caused other failures. In subsequent flight simulation testing, with all known collateral failures included in the simulation, only pilots who were aware of Flight 191's specific problems were able to recover successfully. Although McDonnell Douglas employees participated in an "I'm proud of the DC-10" campaign, the company's shares fell more than 20% following the crash of Flight 191. The DC-10 itself acquired a bad reputation, but ironically it was often caused by poor maintenance procedures, and not design flaws. In 1997 the McDonnell Douglas company was taken over by its rival, Boeing, which moved their corporate headquarters from Seattle to Chicago. Despite the safety concerns, the DC-10 went on to outsell its closest competitor, the Lockheed L-1011, by nearly 2 to 1. [READ THE REST OF THIS ARTICLE]

The Rheinmetall 120-millimeter (4.7 in) gun is a smoothbore tank gun designed and produced by the German Rheinmetall-DeTec AG company. It was developed in response to Soviet advances in armor technology and development of new armored threats. With production beginning in 1974, the first version of the gun, known as the L/44, was used on the German Leopard 2, and was soon exported to be used on tanks such as the American M1 Abrams tanks. It has also been exported to South Korea and Japan, as well as nations which have procured the Leopard 2 and the M1 Abrams. Rheinmetall's 120-millimeter (4.7 in) L/44 tank gun has a length of 5.28 meters (5.77 yd), while the gun system weighs approximately 3,317 kilograms (7,310 lb). However, by 1990 the L/44 was not considered powerful enough to deal with modernized Soviet armor, such as the T-80B, which stimulated an effort by Rheinmetall to develop a better main armament. This first revolved around a 140-millimeter tank gun, but later turned into a compromise which led to the development of an advanced 120-millimeter gun. This gun was the L/55, based on the same internal geometry as the L/44 and installed in the same breech and mount. The L/55 is 1.3 meters (1.4 yd) longer, allowing for an increase in muzzle velocity for ammunition being fired through it. This gun was retrofitted into German and Dutch Leopard 2s, and chosen as the main gun of the Spanish Leopard 2E and Greek Leopard 2HEL. A variety of ammunition has been developed for use by tanks armed with Rheinmetall's tank gun. This includes a series of kinetic energy penetrators, such as the American M829 series, and chemical energy anti-tank warheads. Recent ammunition includes a wide range of new anti-personnel rounds and demolition munitions, giving tanks armed with Rheinmetall's tank gun greater versatility on the modern battlefield. The LAHAT, developed in Israel, is a gun-launched missile which has received interest from Germany and other Leopard 2 users, and is designed to defeat both enemy armor and enemy combat helicopters. The Israelis also introduced a new anti-personnel munition, which limits collateral damage by controlling the fragmentation of the projectile when fired. [READ THE REST OF THIS ARTICLE] is not affiliated with or endorsed by wikipedia. wikipedia and the wikipedia globe are registered trademarks of
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