Which of the following statements is not an assumption used in models of galaxy formation?
A) The very early universe had an almost perfectly uniform distribution of hydrogen and helium gas.
B) Some regions in the universe were slightly more dense than others.
C) The universe is expanding.
D) Gas contracted to form the disks of galaxies before any stars were born.
D) Gas contracted to form the disks of galaxies before any stars were born.
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Is it possible, according to Einstein's relativity, for a child to be biologically older than his or her parents?
A) Yes, if the parents go on a long and fast trip and return to Earth. B) Yes, if the child goes on a long and fast trip and returns to Earth. C) No, because it is not possible to actually move backward through time. D) No, because the principles of relativity don't have anything to do with actual biological aging. E) No, because the "relativity of time" does not allow the actual order of events in time to be switched around.
All of the following statements about the Sun's corona are true. Which one explains why it is a source of X-rays?
A) The temperature of the corona's gas is some 1 to 2 million Kelvin. B) The corona lies above the visible surface of the Sun. C) The corona's gas consists mostly of hydrogen and helium. D) The corona's structure is largely shaped by magnetic fields.
The Hubble Law does not work for nearby galaxies because
A. nearby galaxies are contracting rather than expanding. B. it is difficult to take the spectrum of nearby galaxies as compared to distant galaxies. C. the Hubble law works for all galaxies; distance doesn't matter. D. the speed of nearby galaxies is affected by their gravitational interaction with one another.
By operating a reversible heat engine with an ideal gas as the working substance in a Carnot cycle and measuring the ratio Qc/Qh, we can calculate
a. n, the number of moles of the ideal gas. b. the ratio Vc/Vh of the volumes of the ideal gas. c. the ratio Pc/Ph of the pressures of the ideal gas. d. the ratio PcVc/PhVh of the products of volumes and pressures of the ideal gas. e. the value of Avogadro's number.