The spectrum of a star shows the 656 nm absorption line shifted to 654 nm. Which of the following can we conclude about this star?
A. The star is spinning rapidly.
B. The star is approaching us with an approximate speed of 1,800 km/sec.
C. The star is receding with an approximate speed of 1,800 km/sec.
D. The star is approaching us with an approximate speed of 900 km/sec.
E. The star is receding with an approximate speed of 900 km/sec.
Answer: D
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Which Apollo mission never made it to the lunar surface?
a. Apollo 11 b. Apollo 12 c. Apollo 13 d. Apollo 14 e. Apollo 15
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.
When two bulbs are connected in series to a battery, the electric resistance that the battery senses is
A) greater than the resistance of either bulb. B) less than the resistance of either bulb. C) none of the above
Negative charges, when released, accelerate toward regions of lower electric potential
Indicate whether the statement is true or false