If the hypothesis tracing the extinction of the dinosaurs to an impact is correct, the dinosaurs died off largely because ________
A) the impact caused massive earthquakes worldwide
B) radiation from iridium in the asteroid caused the dinosaurs to die of cancer
C) of global climate effects initiated by dust and smoke that entered the atmosphere after the impact
D) of injuries suffered from direct hits of pieces of the asteroid or comet
C
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Green light emitted by excited mercury vapor corresponds to an energy transition in the mercury atom. A more energetic transition might emit
A) red light. B) blue light. C) white light. D) any of these
The force P needed to hold the 2-m-radius circular arc gate in the position shown is nearest:
(A) 58 kN
(B) 49 kN
(C) 39 kN
(D) 27 kN
Single-Slit Diffraction: Radio waves are diffracted by large objects such as buildings, whereas light is not noticeably diffracted. Why is this?
A. Radio waves are unpolarized, whereas light is normally polarized. B. The wavelength of light is much smaller than the wavelength of radio waves. C. The wavelength of light is much greater than the wavelength of radio waves. D. Radio waves are coherent and light is usually not coherent. E. Radio waves are polarized, whereas light is usually unpolarized.
Which of the following is an example of a longitudinal wave?
a. sound wave in air b. wave traveling in a string c. both a and b d. neither a nor b