How are interstellar bubbles made?
A) by the collapse of a gas cloud to form stars
B) by the rapidly rotating magnetic fields of pulsars
C) by the winds of massive stars and supernovae explosions
D) by the ejection of planetary nebulae from low-mass stars
E) by collisions between the Milky Way and satellite dwarf galaxies
C
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All wavelengths of light travel at the same speed in a vacuum, and carry the same energy per photon
Indicate whether the statement is true or false
A horizontally-projected beam of electrons travelling at 55 km/s travels between two parallel plates between which there is an electric field. The beam travels exactly horizontally the whole time it is between the plates. What does this imply about the electric field between the plates?
A. It is 0. B. It is 56 pV/m upward. C. It is 56 pV/m downward. D. It doesn’t imply anything in particular.
Conversion of Units: Wall posters are usually sold curled up in cylindrical cardboard tubes. If the length of the tube is 0.845 m, and the inside diameter of the tube is 2.40 mm, what is the area of the poster expressed in square centimeters to the correct number of significant figures? (Assume the poster is just as long as the tube and does not overlap itself.)
A. 202.8 cm2 B. 637.1 cm2 C. 203 cm2 D. 319 cm2 E. 637 cm2
Venus has an unusual rotation rate because
a. it is very slow. b. it is very slow and retrograde. c. its obliquity is 90 degrees. d. it is very fast. e. it is very fast and retrograde.