Problem: Density is also an important physical property of matter. The concept of density combines what we know about an objects mass and volume. Density reflects how closely packed the particles of matter are. When particles are packed together more tightly, matter is more dense. Differences in density of matter explain many phenomena. It explains why helium balloons rise. It explains why currents such as the Gulf Stream flow through the oceans. It explains why some things float in or sink. You can see this in action by pouring vegetable oil into water. You can see a colorful demonstration in this video.

Question: "Why is density important?"

Answer: "It's a physical property of matter"
Answer: yes

Problem: At the conference room table was White House Deputy Chief of Staff Joshua Bolten. Bolten watched the exchanges and, after what he called "a quiet moment,"suggested that the Vice President get in touch with the President and confirm the engage order. Bolten told us he wanted to make sure the President was told that the Vice President had executed the order. He said he had not heard any prior discussion on the subject with the President. The Vice President was logged calling the President at 10:18 for a twominute conversation that obtained the confirmation. On Air Force One, the President's press secretary was taking notes; Ari Fleischer recorded that at 10:20, the President told him that he had authorized a shootdown of aircraft if necessary. Minutes went by and word arrived of an aircraft down in Pennsylvania. Those in the shelter wondered if the aircraft had been shot down pursuant to this authorization. At approximately 10:30, the shelter started receiving reports of another hijacked plane, this time only 5 to 10 miles out. Believing they had only a minute or two, the Vice President again communicated the authorization to "engage or "take out" the aircraft. At 10:33, Hadley told the air threat conference call: "I need to get word to Dick Myers that our reports are there's an inbound aircraft flying low 5 miles out. The Vice President's guidance was we need to take them out." Once again, there was no immediate information about the fate of the inbound aircraft. In the apt description of one witness, "It drops below the radar screen and it's just continually hovering in your imagination; you don't know where it is or what happens to it." Eventually, the shelter received word that the alleged hijacker 5 miles away had been a medevac helicopter. Transmission of the Authorization from the White House to the Pilots The NMCC learned of United 93's hijacking at about 10:03. At this time the FAA had no contact with the military at the level of national command. The NMCC learned about United 93 from the White House.

Question: "Who was a part of this conversation?"

Answer: ""Vice President""
Answer: no

Problem: Have you ever seen an egg? Some animals do not have live births. Instead, they lay eggs. The eggs contain the embryo. The embryo matures in the egg. With time, it will hatch. Some animals hatch and do not need care from their parents. They are ready to live on their own. Other animals will still need the care of their parents. Sea turtles break out of their shells. They immediately walk to the ocean. They do this with no help from an adult. Birds stay in the nest for many weeks. They are cared for by their parents. They leave the nest when they are strong enough to fly. Some animals give birth to live offspring. Animals like horses, cows, and whales give live birth. Their offspring are born looking like mini adults.

Question: "Do Sea Turtles need help from their families?"

Answer: "No"
Answer:
yes