Problem: Energy often changes from one form to another. For example, the drummer transfers motion to sound energy. When the moving drumstick strikes the drum head, the drum starts to vibrate. The motion of the vibrating drum head creates the sound you hear. Any form of energy can change into any other form. Frequently, one form of energy changes into two or more different forms. Have you ever sat in front of a campfire? What are two things you notice? The fire creates light. It is also warm by the fire, meaning it creates heat. The energy of the fire comes from the stored energy in the wood. The wood contains chemical energy. As it burns, the chemical energy is changed into light and heat. Not all chemical energy changes produce light and heat. Our cars use gasoline as a fuel. Gasoline contains chemical energy. When our cars burn gasoline in their engines, it is converted into motion and heat. When energy changes forms, energy is conserved.

Question: "What type of energy do cars use to move?"

Answer: "Heat energy"

OPTIONS:
- no
- yes
Answer: no

Problem: You may wonder if there are other examples of static discharge. The answer is yes. Lightning is a form of static discharge. It is much more dramatic than what happens between you and the door knocker, but it is the same principle. You can see how it occurs in the following diagram and animation. You have no doubt seen lightning in a rainstorm. What does lighting have to do with static electricity? As it turns out, everything! During a rainstorm, clouds develop regions of different charges. This happens due to the movement of air molecules, water drops, and ice particles. The negative charges are concentrated at the base of the clouds. The positive charges are concentrated at the top. The negative charges repel electrons on the ground below. The ground then becomes positively charged. Over time the differences increase. Eventually the electrons are discharged. This is what we see as lightning. You can watch an awesome slow-motion lightning strike below.

Question: "What are two examples of static discharge?"

Answer: "Lightning, and what happens between you and a door knocker"

OPTIONS:
- no
- yes
Answer: yes

Problem: The Agencies Confer When they learned a second plane had struck the World Trade Center, nearly everyone in the White House told us, they immediately knew it was not an accident. The Secret Service initiated a number of security enhancements around the White House complex. The officials who issued these orders did not know that there were additional hijacked aircraft, or that one such aircraft was en route to Washington. These measures were precautionary steps taken because of the strikes in New York. The FAA and White House Teleconferences. The FAA, the White House, and the Defense Department each initiated a multiagency teleconference before 9:30. Because none of these teleconferences-at least before 10:00- included the right officials from both the FAA and Defense Department, none succeeded in meaningfully coordinating the military and FAA response to the hijackings. At about 9:20, security personnel at FAA headquarters set up a hijacking teleconference with several agencies, including the Defense Department. The NMCC officer who participated told us that the call was monitored only periodically because the information was sporadic, it was of little value, and there were other important tasks. The FAA manager of the teleconference also remembered that the military participated only briefly before the Pentagon was hit. Both individuals agreed that the teleconference played no role in coordinating a response to the attacks of 9/11. Acting Deputy Administrator Belger was frustrated to learn later in the morning that the military had not been on the call. At the White House, the video teleconference was conducted from the Situation Room by Richard Clarke, a special assistant to the president long involved in counterterrorism. Logs indicate that it began at 9:25 and included the CIA; the FBI; the departments of State, Justice, and Defense; the FAA; and the White House shelter. The FAA and CIA joined at 9:40. The first topic addressed in the White House video teleconference-at about 9:40-was the physical security of the President, the White House, and federal agencies. Immediately thereafter it was reported that a plane had hit the Pentagon. We found no evidence that video teleconference participants had any prior information that American 77 had been hijacked and was heading directly toward Washington.

Question: "To what did the CIA and FAA begin participating in at 9:40?"

Answer: "Teleconference regarding the Plane"

OPTIONS:
- no
- yes
Answer:
yes