So what is gravity? A typical definition of gravity is that it is a force. It causes an attraction between two masses. According to this definition, anything that has mass exerts a force. Any object exerts gravity on other objects. It does not matter how small it is, it has gravity. The more matter an object has, the more gravity it has. Your pencil has a tiny bit of gravity, but far too little to notice. What about a planet? It would have a lot of gravity. An objects gravity exerts a pull on other objects. Friction only occurs between objects that are touching. Gravity can act between objects that are not touching. In fact, gravity can act over very long distances. Where else can you feel gravity?

Question: "Does size matter when it comes to gravity?"

OPTIONS:
- no
- yes

Answer: "Friction only occurs between objects that are not touching"

Response: no

Hundreds of thousands of years before China was to become the world's longest-running civilization, the prologue was enacted by means of the flicker of a carefully tended fire. Peking Man, a forebear of Homo sapiens, achieved a mastery of fire. We might call it the first Chinese invention. Not that he devised flint and steel, matches, or any other way of creating fire. Peking Man simply learned how to capture flame, perhaps from a forest fire, and keep it alight. He thus enjoyed two revolutionary luxuries: light and heat. Technologically and sociologically, it was a phenomenal breakthrough: with fire, communities could live year 'round in one cave, in which cooking and even smelting could be pursued. And so, by 600,000 b.c., about 50 km (31 miles) southwest of present-day Beijing, the ancestors of mankind were ready to settle down. Several hundred thousand years later, when Marco Polo reached the capital of China, he was astonished by a further development in fire technology. The Chinese, he announced, used black stones dug out of mountains as fuel. Europeans did not yet have a word for "coal," nor had they discovered a use for it. The First Dynasty The confluence of mythology and history in China took place around 4,000 years ago during what is referred to as the Xia (Hsia) Dynasty. This was still the Stone Age, but the people are thought to have made silk from thread produced by the worms they cultivated on the leaves of their mulberry trees. And written language (which evolved as early as 4,500 to 5,000 years ago) was already in use, originally by oracles and then by official scribesChina's first scholars. During the second of the quasi-legendary dynasties, the Shang (from about the 16th to 11th centuries b.c.), the Chinese developed an interest in art. Careful geometric designs as well as dragon and bird motifs adorned bowls and implements. And with the arrival of the Bronze Age, the Chinese created bronze vessels of such beauty and originality that, until modern times, archaeologists refused to believe they were cast 3,000 years ago. The Shang Dynasty gave rise to the concept of one Chinese nation under one government.

Question: "Where did man get fire and what luxuries did it provide?"

OPTIONS:
- no
- yes

Answer: "Light and heat"

Response: yes

In October 1933 Einstein returned to the U.S. and took up a position at the Institute for Advanced Study (in Princeton, New Jersey), noted for having become a refuge for scientists fleeing Nazi Germany. At the time, most American universities, including Harvard, Princeton and Yale, had minimal or no Jewish faculty or students, as a result of their Jewish quota which lasted until the late 1940s. Einstein was still undecided on his future. He had offers from several European universities, including Oxford where he stayed for three short periods between May 1931 and June 1933, however in 1935 he arrived at the decision to remain permanently in the United States and apply for citizenship. Einstein's affiliation with the Institute for Advanced Study would last until his death in 1955. He was one of the four first selected (two of the others being John von Neumann and Kurt Godel) at the new Institute, where he soon developed a close friendship with Godel. The two would take long walks together discussing their work. Bruria Kaufman, his assistant, later became a physicist. During this period, Einstein tried to develop a unified field theory and to refute the accepted interpretation of quantum physics, both unsuccessfully.

Question: "Who did Einstein take long walks with?"

OPTIONS:
- no
- yes

Answer: "Godel"

Response: yes

Breathing is the process of moving air into and out of the lungs. The process depends on a muscle called the diaphragm. This is a large, sheet-like muscle below the lungs. Inhaling, or breathing in, occurs when the diaphragm muscle tightens. This increases the size of the chest. This too decreases air pressure inside the lungs. This action allows air and gases to enter the lungs. Exhaling, or breathing out, occurs when the diaphragm muscle relaxes. This decreases the size of the chest. This increases air pressure inside the lungs. This action allows for air to leave the lungs. When you inhale, air enters the respiratory system through your nose and ends up in your lungs, where gas exchange with the blood takes place. What happens to the air along the way? In the nose, mucus and hairs trap any dust or other particles in the air. The air is also warmed and moistened. Next, air passes through a passageway that is connected to the windpipe. The air then finds its way to the lungs. In the chest, the windpipe splits so that air enters both the right and left lung.

Question: "What happens to the air pressure inside the lungs when the diaphragm muscle tightens?"

OPTIONS:
- no
- yes

Answer: "decreases"

Response:
yes