Problem: Except for their color, there are two identical inflatable chairs in a grade school classroom that the children can use during free time. Today, Patrick and Mark, who weighs much more than Patrick, are allowed to use the chairs. Patrick chooses to sit on the red chair, and Mark sits on the green chair. The boys have fun reading books while they sit on their comfortable inflatable chairs. Which chair has a higher air pressure? Hint: What does popping bubble wrap have to do with science? Actually, it demonstrates an important scientific law, called Boyle's law. Like other laws in science, this law describes what always happens under certain conditions. Boyle's law is one of three well-known gas laws, which state the relationships among temperature, volume, and pressure of gases. (The other two gas laws are Charles' law and Amontons' law.) According to Boyle's law , if the temperature of a gas is held constant, then decreasing the volume of the gas increases its pressureand vice versa. That's what happens when you squeeze the bubbles of bubble wrap. You decrease the bubbles' volume, so the air pressure inside the bubbles increases until they pop.

A: green chair

Problem: Kelsey is bored in class, and sees a coil of wire with electricity running through it. There is a box of random pieces of iron on the teacher's desk so she goes and picks up two of them. Piece A she simply puts on her desk to use later, and Piece B she slowly passes through the coil of wire. Which piece of iron is more magnetized? Hint: Our knowledge of electromagnets developed from a series of observations. In 1820, Hans Oersted discovered that a current-carrying wire produced a magnetic field. Later in the same year, Andre-Marie Ampere discovered that a coil of wire acted like a permanent magnet and Francois Arago found that an iron bar could be magnetized by putting it inside of a coil of current-carrying wire. Finally, William Sturgeon found that leaving the iron bar inside the coil greatly increased the magnetic field.

A: Piece B

Problem: Two sister cities were both situated on plate boundaries, close to volcanoes, on different continents. Red city was 10 miles from a volcano, while Tree city was 60 miles away. Red city experienced many earthquakes, Tree city few and far between. Which city experienced fewer rocks breaking? Hint: Almost all earthquakes occur at plate boundaries. All types of plate boundaries have earthquakes. Convection within the Earth causes the plates to move. As the plates move, stresses build. When the stresses build too much, the rocks break. The break releases the energy that was stored in the rocks. The sudden release of energy creates an earthquake. During an earthquake the rocks usually move several centimeters or rarely as much as a few meters. Elastic rebound theory describes how earthquakes occur ( Figure below ).

A: Tree

Problem: John is a nuclear scientist who works at the Fermi lab. Today, in front of him he has four samples, sample A, sample B, sample C, and sample D. Sample A is the naturally occurring uranium. Sample B is enriched uranium. Sample C is the U-238, and sample D is the U-235. He needs to figure out how to best use them. Would sample A have higher or lower percentage of uranium-235 than sample B? Hint: Naturally occurring uranium is composed almost entirely of two isotopes, uranium-238 (99%) and uranium-235 (1%). It is the uranium-235 that is fissionable (will undergo fission) and therefore, this is the uranium isotope than can be used for fuel in a nuclear reactor. For uranium to be used as fuel, the percent of uranium-235 must be increased to at least 3%. Uranium in which the U-235 content is more than 1% is called enriched uranium. Somehow, the two isotopes must be separated so that enriched uranium is available for use as fuel. Separating the isotope by chemical means (chemical reactions) is not successful because the isotopes have exactly the same chemistry. The only essential difference between U-238 and U-235 is their atomic masses; as a result, the two isotopes are separated by a physical means that takes advantage of the difference in mass.

A:
lower