Q&A Hero

Q: An observer moving with a light clock in a spaceship sees a light flash bouncing up and down between parallel mirrors in 1 nanosecond. An observer at rest outside the spaceship sees the same up-and-down flash in A) 1 nanosecond also. B) less than 1 nanosecond. C) more than 1 nanosecond.

Q: You and a friend can share the same space and time measurements when A) you are side by side at rest. B) you both are side by side moving at constant velocity. C) either of these D) none of these

Q: All events and all things exist in "the spacetime continuum" with coordinates A) of distances in three dimensions. B) of time. C) both of these D) none of these

Q: When you run along the hall from one classroom to another you're moving through A) space. B) time. C) both of these D) none of these

Q: Event A occurs before event B in a certain frame of reference. In another frame of reference, event A could occur A) after event B. B) simultaneous with event B. C) either of these D) neither of these

Q: Two lightning bolts are seen to strike two distant locations at the same time. Seen from a different location, the two lightning bolts A) will also be seen at the same time. B) will not be seen at the same time. C) may or may not be seen at the same time.

Q: According to Einstein, events that are simultaneous in one frame of reference A) are simultaneous in all frames of reference. B) are not simultaneous in other frames of reference. C) may or may not be simultaneous in other frames of reference.

Q: A postulate of special relativity is that the speed of light A) like all motion, is relative. B) for all observers is a constant. C) both of these D) neither of these

Q: How fast would a light beam appear to Einstein if he were traveling in the same direction at 90% of the speed of light? A) 0 B) c C) 0.1c D) 1.10c E) none of the above

Q: According to the special theory of relativity, all laws of nature are the same A) in all reference frames. B) for both linear or circular motion. C) in all uniformly moving reference frames. D) all of the above E) none of the above

Q: What is special about the ratio distance traveled per unit of time? A) it is constant for light B) it is relative to a frame of reference C) distance traveled very much depends on time

Q: The speed of light is A) relative to the frame of reference from which it is measured. B) a speed approached but never quite reached by photons. C) constant for all observers.

Q: Einstein rejected the classical idea that space and time are A) two parts of a whole. B) connected to each other. C) independent of each other.

Q: The ether theory of light propagation is A) much used. B) incomplete, but still useful. C) unexplained. D) discredited.

Q: To the surprise of Michelson and Morley, their interferometer experiment provided evidence that the speed of light is A) invariant. B) the same whether its source approaches or recedes. C) constant. D) all of the above

Q: The place from which motion is observed and measured is called A) a frame of reference. B) a starting point. C) an initial location.

Q: The most abundant element in the universe is A) hydrogen. B) helium. C) lead. D) uranium.

Q: Earth's interior is warmed by ________ and Earth's surface is warmed by ________. A) radioactive processes; fusion in the Sun B) fission; fossil fuels C) volcanoes; solar energy D) terrestrial radiation; terrestrial radiation

Q: Sustained energy output by fusion is a daily occurrence in A) military installations. B) breeder reactors. C) the Sun. D) Earth's interior.

Q: Early 21st Century research in nuclear fusion uses A) laser beams. B) ultra-hot plasmas. C) both of these D) neither of these

Q: Deuterium and tritium are both A) forms of hydrogen. B) isotopes of the same element. C) both of these D) neither of these

Q: Compared with the energy produced by fissioning a gram of uranium, the energy produced by fusing a gram of deuterium is A) more. B) less. C) the same.

Q: Fusing two iron nuclei would occur with A) absorption of energy. B) release of energy. C) neither of these

Q: Fusing two carbon nuclei would occur with A) absorption of energy. B) release of energy. C) neither of these

Q: Fissioning carbon would occur with A) absorption of energy. B) release of energy. C) neither of these

Q: Iron is a poor choice of nuclear fuel because it releases A) energy only when fused. B) energy only when fissioned. C) no energy when fused or fissioned.

Q: If oxygen were used as nuclear fuel, it would be best A) fused. B) fissioned. C) either of these

Q: If gold were used as nuclear fuel, it would be best A) fused. B) fissioned. C) either of these

Q: When U-235 undergoes fission, the total number of protons in the fragments is A) 90. B) 91. C) 92. D) 93. E) none of the above

Q: Detonation of a fusion-type hydrogen bomb begins by A) splitting uranium. B) pressing together pieces of uranium. C) igniting a fission bomb. D) all of the above E) none of the above

Q: Detonation of a fission-type uranium bomb begins by A) splitting uranium. B) pressing together pieces of uranium. C) igniting a small conventional bomb. D) all of the above E) none of the above

Q: When two light atoms fuse together, mass A) converts to kinetic energy. B) converts to high-energy gamma radiation. C) is created from energy of other forms. D) is gained.

Q: An element is changed into a completely different element in A) radioactive alpha decay. B) radioactive beta decay. C) nuclear fission. D) nuclear fusion. E) all of the above

Q: In both fission and fusion, mass A) is created from energy of other forms. B) converts to kinetic energy. C) converts to gamma radiation. D) remains the same.

Q: Fissioning an iron nucleus would occur with A) absorption of energy. B) release of energy. C) neither absorption nor release of energy

Q: In both fission of uranium and fusion of hydrogen, mass A) decreases. B) remains constant. C) increases.

Q: According to the "energy valley" of the mass-per-nucleon versus atomic-number graph, the element with the least mass per nucleon is A) hydrogen. B) helium. C) iron. D) uranium. E) none of the above

Q: Between the processes of nuclear fission and fusion, radioactive by-products are more characteristic of nuclear A) fission. B) fusion. C) both of these D) neither of these

Q: The nuclear process having by-products with least radioactivity is A) fission. B) fusion. C) about the same for both.

Q: The energy released in both fission and fusion is mainly in the form of A) kinetic energy of fragments. B) alpha radiation. C) beta radiation. D) gamma radiation. E) none of the above

Q: Energy released by the Sun results from the process wherein atomic nuclei A) break apart. B) combine. C) both of these D) neither of these

Q: An important feature of the mass spectrometer is that A) all ions enter the device at equal speeds. B) ions of different masses bend differently. C) the greater an ion's mass, the wider its circular arc. D) a magnetic field exerts forces on moving charged particles. E) all of the above

Q: A mass spectrometer separates A) ions of different elements. B) different-mass ions of the same element. C) different-mass ions of the same speed. D) all of the above E) none of the above

Q: Various singly-ionized atomic nuclei of the same speed are directed into a magnetic field in a mass spectrometer where they are deflected and strike a detecting screen. The particles most strongly deflected are those of A) least mass. B) greatest mass. C) same for all

Q: Compared with the sum of isolated-nucleon masses, their collective mass in a composite nucleus is A) more. B) less. C) the same.

Q: Fissioning a lead nucleus would yield a net A) absorption of energy. B) release of energy. C) neither of these

Q: The nucleus having the most tightly bound nucleons is A) hydrogen. B) iron. C) lead. D) uranium. E) plutonium.

Q: The nucleus that has the greatest mass per nucleon is A) hydrogen. B) iron. C) lead. D) uranium. E) plutonium.

Q: The nucleus that has the least mass per nucleon is A) hydrogen. B) iron. C) lead. D) uranium. E) plutonium.

Q: Which of these nuclei has the least mass? A) hydrogen B) iron C) lead D) uranium E) all the same

Q: A nucleon has more mass on average when it is A) inside the nucleus. B) removed from the nucleus. C) both the same

Q: The products of nuclear fission are radioactive due to their A) combustive natures. B) capacity to hold vast amounts of energy. C) greater neutron to proton ratio compared with stable nuclei in the same mass range. D) short half-lives. E) none of the above

Q: To pluck a nucleon from a nucleus requires A) work. B) kinetic energy. C) potential energy. D) none of the above

Q: What is the central equation of mass-energy equivalence? A) W = Fd B) KE = mv2 C) m = F/a D) E = mc2

Q: The fact that more radioactive particles are spewed from coal-fired power plants than nuclear fission reactors is evidence that A) coal is more radioactive than uranium. B) coal-fired plants have less shielding. C) coal-fired plants are more numerous. D) all of the above E) none of the above

Q: The disadvantages to fission power plants include A) radioactive waste disposal. B) production of plutonium for possible weapons proliferation. C) risk of accidental release of radioactivity. D) all of the above E) none of the above

Q: Relative to a fossil-fuel plant, a nuclear power plant produces A) more electricity. B) less heat and smoke. C) less pollution. D) all of the above E) none of the above

Q: The percentage of electricity from nuclear power generated in recent decades in the United States has been about A) 10%. B) 20%. C) 30%. D) 40%. E) more than 40%

Q: The energy output of a typical nuclear reactor is via A) heating water to form steam. B) directing steam to a turbine. C) spinning a turbine to generate electricity. D) all of the above E) none of the above

Q: Plutonium is extremely rare in natural ore deposits because it A) is artificially created. B) is chemically inert. C) is a gas at room temperature. D) has a tiny half-life compared with the age of Earth. E) none of the above

Q: When a nucleus of U-238 absorbs a neutron and becomes U-239, a beta emission, then another beta emission results in A) Th-239. B) Pa-239. C) U-235. D) Pu-239. E) Pb-206.

Q: Plutonium is radioactively toxic A) in any form. B) although less toxic than radium. C) both of these D) neither of these

Q: If all the uranium in the world were exhausted, breeder reactors would be A) in greater demand. B) relics of a brief age. C) both of these D) neither of these

Q: Reactions that take place in a breeder reactor change A) elements into different elements. B) molecules into different molecules. C) ions into different ions. D) all of the above E) none of the above

Q: What does a breeder reactor "breed?" A) more energy output than energy input B) fissionable isotopes from a non-fissionable isotopes C) more mass than it begins with D) all of the above E) none of the above

Q: Although plutonium alone is chemically toxic, it is not toxic when A) oxidized. B) ionized. C) subcritical. D) none of the above

Q: U-235 and Pu-239 are both A) radioactive isotopes. B) fissionable isotopes. C) heavier than lead. D) all of the above E) none of the above

Q: When neptunium emits a beta particle the result is A) a different isotope of neptunium. B) uranium. C) plutonium. D) lead. E) none of the above

Q: Carbon was used in Fermi's first nuclear reactor to A) slow neutrons. B) increase the speed of neutrons. C) absorb neutrons. D) none of the above

Q: Compared with a neutron bouncing off a carbon nucleus, a neutron bouncing off an iron nucleus loses A) less speed. B) more speed. C) the same amount of speed.

Q: A neutron bouncing off a heavy nucleus loses speed. If it instead bounces off a light nucleus it loses A) less speed. B) more speed. C) the same amount of speed.

Q: A neutron will more likely slow in speed if it bounces from a A) light-weight nucleus. B) nucleus of moderate mass. C) heavy nucleus. D) none of the above

Q: The function of graphite in the first atomic reactor was to A) slow fast neutrons. B) emit fast neutrons. C) moderate uranium isotopes. D) none of the above

Q: Neutrons that will initiate the fission of U-235 require speeds that are A) less than average. B) about average. C) more than average. D) all of the above E) none of the above

Q: Two isotopes that undergo nuclear fission are A) U-235 and Pu-239. B) Th-238 and U-235. C) all of these D) none of these

Q: The water that operates a fission-reactor turbine is A) not the same water that flows through the reactor. B) heated to high-pressure steam. C) without radioactivity. D) all of the above E) none of the above

Q: The possible fate of a neutron in ordinary uranium metal is to A) cause fission of U-235 if present. B) escape the metal. C) be absorbed by U-238 without causing fission. D) all of the above E) none of the above

Q: Control is maintained in a nuclear reactor by control rods that A) absorb excess neutrons. B) emit fast neutrons. C) both of these D) neither of these

Q: The kinetic energy of fission fragments in a nuclear reactor A) superheats water and produces steam. B) converts to gamma-ray radiation. C) becomes radioactive pollution. D) converts directly to electricity. E) none of the above

Q: A nuclear power plant is very similar to A) nuclear bombs, but with more control. B) any conventional power plant, but with uranium as fuel. C) a photovoltaic solar cell power plant. D) all of the above E) none of the above