Summarize the links in the distance chain that allow us to estimate distances to the farthest reaches of the universe
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We can determine the distance to solar system objects through radar ranging. This gives us an accurate distance to the Sun so that we can use stellar parallax to measure the distances to the nearest stars. Since there is a period-luminosity relationship for Cepheids, we can measure the distances to other Cepheids by just measuring the time period between peaks of brightness. Cepheids are bright enough to be observed in galaxies other than the Milky Way. Therefore, they serve as a bridge between us and standard candles in other galaxies. Once we determine the distance to another galaxy for which we have observed a white-dwarf supernova, we then can calibrate the average luminosity of white-dwarf supernovae. White-dwarf supernovae and Cepheids get us far enough away from the Milky Way that we then can calibrate Hubble's law by determining the Hubble constant. Once we know the Hubble constant, we will be able to determine a galaxy's distance from its redshift.
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Compare insulators and conductors on the atomic level
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Energy and Mass: If the mass of a 1.0-kg book could be entirely converted into electrical energy, how many kW ? h of energy would that generate? (c = 3.0 × 108 m/s)
Fill in the blank(s) with the appropriate word(s).
Which type of reflector telescope would be the easiest to construct, and why?
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Two protons are fired toward each other in a particle accelerator, with only the electrostatic force being exerted. Which of the following statements must be true about them as they move closer together? (There could be more than one correct choice)
A) The electric potential energy of the system of the two protons keeps increasing. B) Their kinetic energy keeps increasing. C) The electric potential energy of the system of the two protons keeps decreasing. D) Their kinetic energy keeps decreasing. E) Their acceleration keeps decreasing.