Light of wavelength 400 nm bombards a surface with work function 2.46 eV. What is the maximum kinetic energy of the photoelectrons from this surface?
A. no photoelectrons are emitted
B. 2.46 eV
C. 3.30 eV
D. 0.640 eV
E. 0.840 eV
D. 0.640 eV
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The "rare Earth hypothesis" holds that Earth-like planets will prove to be quite rare. Which of the following statements best sums up the current status of the debate over this hypothesis?
A) It is no longer discussed, because as part of its broad cover-up of UFOs, the United States government has classified all the material relating to this debate as Top Secret. B) We do not have enough data to settle the debate, because counterarguments can be made for each argument suggesting Earth-like planets may be rare. C) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are rare. D) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are common.
A machine that promises more energy output than input is
A) a fantasy. B) commonplace in today's technology. C) a long-shot worth investing in.
Angular Momentum: An ice skater has a moment of inertia of 5.0 kg ? m2 when her arms are outstretched, and at this time she is spinning at 3.0 rev/s. If she pulls in her arms and decreases her moment of inertia to 2.0 kg ? m2, how fast will she be spinning?
A. 2.0 rev/s B. 3.3 rev/s C. 7.5 rev/s D. 10 rev/s
What do asteroids and comets have in common?
A) They have similar densities. B) They have similar orbital radii. C) Most are unchanged since their formation in the solar nebula. D) They have a similar range of orbital inclinations. E) They have nothing in common with each other.