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Module 16
Module 16
| Question | Answer |
|---|---|
| Nuclear fusion | the process by which two or more small nuclei fuse to make a bigger nucleus |
| nuclear fission | the process by which a large nucleus is split into smaller nuclei |
| critical mass | the amount of isotope necessary to sustain a chain reaction |
| absolute magnitude | the brightness of a star, corrected for distance, on a scale of -8 to +19. The smaller the number, the brighter the star. |
| apparent magnitude | the brightness of a star as seen in the night sky. The smaller the number, the brighter the star. |
| light year | the distance light could travel along a straight line in one year |
| galaxy | a large ensemble of stars, all interacting through the gravitational force and orbiting around a common center |
| From the inside to the outside, name the four regions of the sun. | the core, the radiation zone, the convection zone, and the photosphere. |
| How does the sun gets its power? In which region of the sun does this process occur? | The sun gets its power from nuclear fusion that occurs in the core. |
| What part of the sun do we see? | We see the photosphere. |
| a 251Cf nucleus is bombarded with a neutron. It breaks down into a 124S nucleus, a 120Cd nucleus and seven neutrons. Is this nuclear fission or nuclear fusion? | Since a large nucleus split into two smaller nuclei (and a few neutrons) this is nuclear fission. |
| Two 4He nuclei collide and turn into a 7Be nucleus and one neutron. Is this nuclear fusion or nuclear fission? | Since two small nuclei became a bigger nucleus (plus a neutron), this is nuclear fusion. |
| For both nuclear fusion that occurs in the sun and the nuclear fission that occurs in a nuclear power plant, what can we say about the mass of the starting materials compared to the mass of what's made in the end? | In both processes, mass is converted into energy. Thus, the mass of the starting materials is larger than the mass of the materials the process makes. |
| Why is it impossible for a nuclear power plant to have a nuclear explosion? | It is impossible for a nuclear power plant to experience a nuclear explosion because a power plan does not have significantly more than the critical mass of the large nucleus that is breaking apart. |
| Why is nuclear fusion considered a better option for energy production than nuclear fission? | Nuclear fusion is a better means of producing energy because there are no radioactive byproducts, there is no change of meltdown, and the starting materials are cheap. |
| If nuclear fusion is a better option, why don't we use it? | We cannot use nuclear fusion yet because we cannot master the technology to make it economically feasible. |
| Be able to use an H-R diagram to classify stars | |
| Which of the stars (red giant, main sequence, supergiant, or white dwarf) is most like our sun? | Our sun is a main sequence star. |
| Order these four stars (red giant, main sequence, supergiant, and white dwarf) in terms of increasing size. | White dwarf, main sequence, red giant, and super giant. |
| Order these four stars (red giant, main sequence, supergiant, and white dwarf) in terms of increasing brightness. | Brightness is given by magnitude. The smaller the magnitude the brigher the star. so white dwarf, main sequence, red giant, and super giant. |
| Which of these stars is the coolest - (red giant, main sequence, supergiant, and white dwarf). | The farther to the right on the H-R diagram, the cooler the star - thus the red giant is the coolest. |
| What similarity exists between novas, supernovas, and pulsating variables? | All three of these are variable star types. Thus, their brightness changes radically with time. |
| What is the big difference between novas, supernovas, and pulsating variables? | The big difference between these star types is lifetime. Pulsating stars last a long time, supernovas exist very briefly, and novas are somewhere in between. |
| What most likely formed the crab nebula? | The crab nebula was most likely formed by a supernova. |
| What are the two methods for measuring the distance from earth to a star? Which of the two is the most accurate? Which can be used to measure long distance? | The two methods are the parallax method and the apparent magnitude method. The parallax method is exact, but the apparent magnitude method can be used to measure longer distances. |
| Why are Cepheid variable so important for measuring long distances in the universe? | Cepheid variable are important for measuring long distances because they seem to have a relationship between their period and their magnitude. That allows them to be used in the apparent magnitude method for measuring long distances in the universe. |
| What are the four basic types of galaxies? To which type does the Milky Way belong? | The four galaxy types are spiral, lenticular, elliptical, and irregular. The Milky Way is a spiral galaxy. |
| Star groups together to form _________, which group together to form _________, which group together to form ____________, some of which group together to form __________. | Stars group together to form galaxies, which group together to form groups, which group together to form clusters, some of which group together to form superclusters. |
| The earth's solar system belongs in the ___________, which belongs to the __________, which belongs to the _________. | The earth's solar system belongs in the Milky Way, which belongs to the Local Group, which belongs to the Virgo Cluster. |
| Why do most astronomers believer the universe is expanding? | Most astronomers believe that the universe is expanding because the light from nearly every galaxy experiences a red shift before it reaches the earth, and the red shift increases the farther the galaxy is from the earth. |
| If the universe is expanding, does the geometry of the expansion matter? Is so, why? | Yes, the geometry of the universal expansion makes a great deal of difference. The theories that can be developed for the formation of the universe depend on that initial assumption. |
Created by:
davisjuring
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