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: "What can density explain?"

Answer: "Conductivity"

Response: no

In her storage room-turned-office, Jennifer Baum works under an expanding leak that is causing the ceiling to turn brown and crumble. Mold grows in the buckets positioned to catch the water. She shrugs it off. Outside her office she has taped up a clear plastic suit, and a sign that reads, "All employees must don protective gear before coming in." Such is life in limbo. Nearly a year after Sept. 11, the Legal Aid Society-the lawyers for New York's poor and homeless-remains, well, homeless. The nonprofit has been barred from returning to its 90 Church St. headquarters, across from the World Trade Center site, because of environmental concerns. Legal Aid has uncomfortable company. More than 11,500 New Yorkers continue to work out of temporary space, according to analysis by Manhattan-based real estate brokerage TenantWise.com Inc. and Crain's New York Business. That's 8% of the 137,000 workers who lost their offices or access to them when the Twin Towers collapsed. Legal Aid's 450 displaced attorneys and staffers have spent the past 12 months spread among previously unused spaces-some unused for good reason-in the nonprofit's other offices. It could be another year and a half before they return to their old desks. They have contended with difficult working conditions as demand for Legal Aid's services is on the rise because of Sept. 11 and the deteriorating economy. The civil division is spread among a few boroughs. Their papers and documents, some 20,000 boxes worth, are stuck in a storage facility in Linden, N.J. "I am counting the days till we can have all the parts back in one place," says Steven Banks, Legal Aid's associate attorney in chief. In the memories of the exiled workers, the old office has achieved mythical proportions. They say the wood paneling and rugs had the ability to cool emotions and lift spirits. The Legal Aid office on Montague Street in Brooklyn Heights, where 65 displaced workers have cobbled together space amid the faded and scratched walls, looks more like a bargain basement.

Question: "Why must employees wear protective gear before entering Jennifer Baum's office?"

Answer: "The ceiling is crumbling"

Response: yes

When single father Thurman Williams needed help filling out papers in a custody suit recently, he didn't look to his lawyer for help. He walked to a computerized kiosk at the Lamoreaux Justice Center in Orange and started tapping the keys. As part of a legal experiment, litigants without lawyers across California are using computerized video kiosks to prepare common court filings and seek basic legal advice. The kiosk used by Williams is part of a statewide effort to cope with a flood of litigants who cannot afford or refuse to hire lawyers. Court officials statewide fear the number of self-represented litigants has reached crisis levels and threatens to clog court calendars. Like Williams, more than 6,000 Orange County litigants have initiated court actions on I-CAN! kiosks or accessed the programs on the Internet, using home computers. Similar programs are operating in Sacramento, San Diego and Ventura. A recent study of the kiosks' first 18 months of operation concluded it is too soon to tell if the system will relieve pressure on court calendars. But the report, by UC Irvine's School of Social Ecology, said users were overwhelmingly positive about the free legal assistance. "It's made life a lot easier for me," Williams said. "It's helped keep me from going to the poorhouse." The 29-year-old Orange resident was directed to a kiosk in the Lamoreaux Justice Center by court staff. After putting on headphones and following the directions of a videotaped instructor, Williams filled out a quarter-inch stack of paternity and custody documents. The exercise took 20 minutes; it would have cost him about $800 if he had relied on a lawyer, he said. "It was a lot easier than I thought." Whether they can't afford a lawyer or just want to save money, more Californians are going to court without a lawyer. "I'm just amazed at the numbers," said Commissioner Salvador Sarmiento, who hears between 40 and 90 child-support cases a day in Lamoreaux Justice Center.

Question: "Why did Thurman Williams walk to a computerized kiosk at the Lamoreaux Justice Center in Orange and just start tapping keys, as oppose to finding a lawyer?"

Answer: "Didn't want to go to an office"

Response: no

The center of an atom is held together by powerful forces. This gives them a huge amount of stored energy. This type of energy is called nuclear energy. This energy can be released and used to do work. This happens in nuclear power plants where they split apart the nucleus of an atom. This splitting apart is called nuclear fission. Another type of nuclear energy happens in the Sun. Here the atoms nuclei are not split apart. Instead, the nuclei of the atoms are fused, or joined together. This process is called nuclear fusion. Some of the suns energy travels to Earth. This energy from nuclear fusion warms the planet and provides the energy for photosynthesis.

Question: "What is the process called when the nuclei of the atoms are fused, or joined together."

Answer: "Nuclear fusion"

Response:
yes