9/11

 

9/11 ATTACKS 

On September 11, 2001, 19 Islamic extremist group al-Qaeda hijacked four airplanes and carried out suicide attacks against targets in the United States. Two of the planes were flown into the twin towers of the World Trade Center in New York City, a third plane hit the Pentagon just outside Washington, D.C.,Image result for 9/11 ATTACKS and the fourth plane crashed in a field in Pennsylvania. Two of the planes were flown into the twin towers of the World Trade Center in New York City, a third plane hit the Pentagon just outside Washington, D.C., and the fourth plane crashed in a field in Pennsylvania. A total of 2,996 people were killed in the 9/11 attacks.

The twin towers of the World Trade Center in New York City

On September 11, 2001, at 8:45 a.m. on a clear Tuesday morning, an American Airlines Boeing 767 loaded with 20,000 gallons of jet fuel crashed into the north tower of the World Trade Center in New York City. The impact left a gaping, burning hole near the 80th floor of the 110-story skyscraper, instantly killing hundreds of people and trapping hundreds more in higher floors. As the evacuation of the tower and its twin got underway, television cameras broadcasted live images of what initially appeared to be a freak accident. Then, 18 minutes after the first plane hit, a second Boeing 767—United Airlines Flight 175—appeared out of the sky, turned sharply toward the World Trade Center and sliced into the south tower near the 60th floor.The collision caused a massive explosion that showered burning debris over surrounding buildings and onto the streets below. It immediately became clear that America was under attack. Less than 15 minutes after the terrorists struck the nerve center of the U.S. military, the horror in New York took a catastrophic turn when the south tower of the World Trade Center collapsed in a massive cloud of dust and smoke.The structural steel of the skyscraper, built to withstand winds in excess of 200 miles per hour and a large conventional fire, could not withstand the tremendous heat generated by the burning jet fuel.American Photography At 10:30 a.m., the north building of the twin towers collapsed. Only six people in the World Trade Center towers at the time of their collapse survived. Almost 10,000 others were treated for injuries.

 

As millions watched the events unfolding in New York, American Airlines Flight 77 circled over downtown Washington, D.C., before crashing into the west side of the Pentagon military headquarters at 9:45 a.m. Jet fuel from the Boeing 757 caused a devastating inferno that led to the structural collapse of a portion of the giant concrete building, which is the headquarters of the U.S. Image result for The pentagon crash 9/11Department of Defense. All told, 125 military personnel and civilians were killed in the Pentagon, along with all 64 people aboard the airliner.

United Flight 93

Meanwhile, a fourth California-bound plane—United Flight 93—was hijacked about 40 minutes after leaving Newark Liberty International Airport in New Jersey. Because the plane had been delayed in taking off, passengers on board learned of events in New York and Washington via cell phone and Airfone calls to the ground. Knowing that the aircraft was not returning to an airport as the hijackers claimed, a group of passengers and flight attendants planned an insurrection .The plane then flipped over and sped toward the ground at upwards of 500 miles per hour, crashing in a rural field near Shanksville in western Pennsylvania at 10:10 a.m. All 44 people aboard were killed. Its intended target is not known, but theories include the White House, the U.S. Capitol.Image result for The flight 93 9/11

 

Burj Khalifa Facts

Burj Khalifa Facts

Facts

  • Burj Khalifa can sway up to 3.9 feet.
  • The elevator in Burj Khalifa gose 55 floors per second
  • Burj Khalifa has 163 floors and one floor is underground.
  • Burj Khalifa is  828 metres or 2,716.5 feet.
  • The observatory deck of the building is located at a height of 1483 feet or 452.1 meters.
  •  Burj Khalifa has 58 elevator
  • Burj Khalifa has 304 hotels and 900 apartments.
  • Burj Khalifa has 3,000 car parking spaces on two basement levels.

20 Interesting Facts About Burj Khalifa

Fact About Building Burj Khalifa

Over 12,000 professionals and skilled workers from more than 100 countries were on site every day. Over 45,000 cubic metres 1.59 million cubic feet of concrete, weighing more than 110,000 tonnes, were used to construct the concrete and steel foundations. 330,000 cubic. 11.6 million cubic feet of concrete 39,000  of reinforced steel; 103,000 sq m 1.1 million square feet of glass; 15,500 square 166,800 square feet  of embossed stainless steel and the tower took 22 million man hours to build.  The concrete used is equivalent to a sidewalk 1,900 kilometres 1,200 miles in length, and the weight of 100,000 elephants.

Foundation

The superstructure is supported by a large reinforced concrete mat, which is in turn supported by bored reinforced concrete piles. The mat is 3.7 metres thick, and was constructed in four separate pours totalling 12,500 cubic metres of concrete

20 Facts About Burj Khalifa

MAINTENANCE

  WATER

The tower’s water system supplies an average of 946,000 litres 250,000 gallons of water daily. At peak cooling, Burj Khalifa will require about 10,000 tonnes of cooling  This water is collected and drained in a separate piping system to a holding tank in the basement car park. The condensate collection system provides about 15 million gallons of supplement water per year, equal to about 20 Olympic-sized swimming pools

ELECTRICAL

 

The tower’s peak electrical demand is 36mW, equal to about 360,000 bulbs of 100 watts operating.

Fire Safety & Security

Fire safety and speed of evacuation were prime consideration in the design of Burj Khalifa. Concrete surrounds all stairwells and the building service and fireman’s elevator has a capacity of 5,500 kg and is the world’s tallest service elevator. There are pressurized, air-conditioned refuge areas located approximately every 25 floors.

 

Sun Facts

 

This image is from a simulation of the motion of clouds in Jupiter's Great Red Spot by applying a wind movement model to a mosaic of NASA's JunoCam images.

  1. At its center the Sun reaches temperatures of 15 million degrees °C.
  2. The Sun is all the colors mixed together, this appears white to our eyes.
  3. The Sun is mostly composed of hydrogen 70% and Helium 28%.
  4. The Sun is 4.6 billion years old.
  5. The Sun is 109 times wider than the Earth and 330,000 times as massive.
  6. Image result for sun fact