Which property is common to spiral galaxies?
A) very little internal structure
B) open clusters in the halo
C) globular clusters in the nucleus
D) ongoing star formation and emission nebula in the arms
E) ongoing star formation and emission nebula in the halo
D
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At what stage of evolution do T Tauri stars occur?
A) just as the collapsing cloud becomes luminous B) when a protostar is on the verge of becoming a main sequence star C) just prior to the protostar stage D) just after the planetary nebula is expelled E) after the star has established itself as a main sequence star
Two continuous waves having the same wavelength and amplitude pass through the same medium. They are aligned crest to crest and trough to trough so that they interfere. The resulting wave has
A) the same wavelength and the same amplitude. B) twice the wavelength and twice the amplitude. C) zero amplitude. D) twice the wavelength and the same amplitude (or height) as each of the individual waves. E) the same wavelength and twice the amplitude.
What is the Doppler effect, and how is it produced? Cite two examples
What will be an ideal response?
When an item has been launched into orbit:
a. it no longer falls because the weakening of Earth's gravity with increased height has made it lighter than air. b. it no longer falls because it is outside the atmosphere. c. it is kept in orbit by attraction to the Sun and Moon. d. it continues to fall but its path never reaches the ground. e. centripetal force from Earth's gravity keeps it from being accelerated toward Earth.