If you build a campfire, you start with a large stack of sticks and logs. As the fire burns, the stack slowly shrinks. By the end of the evening, all that is left is a small pile of ashes. What happened to the matter that you started with? Was it destroyed by the flames? It may seem that way. What do you think happened? The truth is that the same amount of matter still exists. The wood changed not only to ashes, but also to carbon dioxide, water vapor, and other gases. The gases floated off into the air, leaving behind just the ashes. Although matter was changed, it was not created or destroyed. Because the same amount of matter still exists, we can say that matter is conserved. You may wonder how it can be conserved if something is now missing? Assume you had measured the mass of the wood before you burned it. Assume you had also trapped the gases released by the burning wood and measured their mass and the mass of the ashes. What would you find? The ashes and gases combined have the same mass as the wood you started with. This example illustrates the law of conservation of mass.

Question: "What happened to the matter changed to when burning a fire?"

Answer: "It changed to other gases"

Response: yes

While Nashiri was in Afghanistan, Nibras and Khamri saw their chance. They piloted the explosives-laden boat alongside the USS Cole, made friendly gestures to crew members, and detonated the bomb. Quso did not arrive at the apartment in time to film the attack. Back in Afghanistan, Bin Laden anticipated U.S. military retaliation. He ordered the evacuation of al Qaeda's Kandahar airport compound and fled- first to the desert area near Kabul, then to Khowst and Jalalabad, and eventually back to Kandahar. In Kandahar, he rotated between five to six residences, spending one night at each residence. In addition, he sent his senior advisor, Mohammed Atef, to a different part of Kandahar and his deputy, Ayman al Zawahiri, to Kabul so that all three could not be killed in one attack. There was no American strike. In February 2001, a source reported that an individual whom he identified as the big instructor (probably a reference to Bin Laden) complained frequently that the United States had not yet attacked. According to the source, Bin Laden wanted the United States to attack, and if it did not he would launch something bigger. The attack on the USS Cole galvanized al Qaeda's recruitment efforts. Following the attack, Bin Laden instructed the media committee, then headed by Khalid Sheikh Mohammed, to produce a propaganda video that included a reenactment of the attack along with images of the al Qaeda training camps and training methods; it also highlighted Muslim suffering in Palestine, Kashmir, Indonesia, and Chechnya. Al Qaeda's image was very important to Bin Laden, and the video was widely disseminated. Portions were aired on Al Jazeera, CNN, and other television outlets. It was also disseminated among many young men in Saudi Arabia and Yemen, and caused many extremists to travel to Afghanistan for training and jihad. Al Qaeda members considered the video an effective tool in their struggle for preeminence among other Islamist and jihadist movements.

Question: "Who attacked the USS cole?"

Answer: "Nibras and Khamri"

Response: yes

Sound waves are mechanical waves. They can travel only through matter. They cannot travel through empty space. This was demonstrated in the 1600s by a scientist named Robert Boyle. Boyle placed a ticking clock in a sealed glass jar. The clock could be heard ticking through the air and glass of the jar. Then Boyle pumped the air out of the jar. The clock was still running, but the ticking could not be heard. Thats because the sound couldnt travel without air particles to transfer the sound energy. Is there any other place where sound cannot be heard? Here is a hint: is there any other place that does not have air molecules? Thats right, in space sound cannot be transferred. So can astronauts hear each other? Yes, they can, because they are in enclosed space stations or pressurized suits.In both cases, they are surrounded by air molecules. If they left their space ship and did not use their electronics, they would not be able to hear each other. Next time you watch a science fiction movie, think about this factoid. When spaceships are destroyed by hostile alien beings, there would be no sound heard. Sound waves can travel through many kinds of matter.

Question: "In Boyle's experiment, what did he do to make the clock stop being heard while in the jar?"

Answer: "He added air to the jar."

Response: no

863. INGREDIENTS.--The remains of a boiled calf's head, 1-1/2 pint of the liquor in which the head was boiled, 1 blade of pounded mace, 1 onion minced, a bunch of savoury herbs, salt and white pepper to taste, thickening of butter and flour, the yolks of 2 eggs, 1 tablespoonful of lemon-juice, forcemeat balls. _Mode_.--Remove all the bones from the head, and cut the meat into nice square pieces. Put 1-1/2 pint of the liquor it was boiled in into a saucepan, with mace, onion, herbs, and seasoning in the above proportion; let this simmer gently for 3/4 hour, then strain it and put in the meat. When quite hot through, thicken the gravy with a little butter rolled in flour, and, just before dishing the fricassee, put in the beaten yolks of eggs and lemon-juice; but be particular, after these two latter ingredients are added, that the sauce does not boil, or it will curdle. Garnish with forcemeat balls and curled slices of broiled bacon. To insure the sauce being smooth, it is a good plan to dish the meat first, and then to add the eggs to the gravy: when these are set, the sauce may be poured over the meat.

Question: "Is the simmering in Sentence 4 done before or after the calf's head is boiled?"

Answer: "Before the calf's head has been boiled"

Response:
no