When the absolute magnitudes, or brightnesses, of stars are plotted against their surface temperatures or colors, we obtain a(n)
a. Hertzsprung-Russell (or H-R) diagram.
b. straight line.
c. random pattern.
d. none of the above
a
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Two forces produce equal torques on a door about the door hinge. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door
Which force has a greater magnitude? A) the first force (at the midpoint) B) the second force (at the doorknob) C) The two forces are equal.
Three pith balls supported by insulating threads hang from a support. We know that ball X is positively charged. When ball X is brought near balls Y and Z without touching them, it attracts Y and repels Z. Since pith is an insulating material, we can conclude that
a. Y has a negative charge. b. Z has a negative charge. c. Y has a positive charge. d. Z is neutral (has no net charge.) e. Y is negatively charged or neutral (has no net charge.)
A long straight metal rod has a radius of 2.0 mm and a surface charge of density 0.40 nC/m2 . Determine the magnitude of the electric field 3.0 mm from the axis
a. 18 N/C b. 23 N/C c. 30 N/C d. 15 N/C e. 60 N/C
Coastal lands bordering the oceans generally have
A) colder temperatures than lands away from the ocean. B) more moderate temperature variations than inland areas. C) more scenery than land in the continental interior. D) tropical temperatures due to the high heat capacity of water.