Which of these is NOT typical of the Galaxy's spiral arms?
A) open clusters
B) Population II giants like orange Arcturus
C) emission nebulae like M42
D) hot, young blue Population I stars
E) O and B stars
B
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An 80-kg man is skating northward and happens to suddenly collide with a 20-kg boy who is ice skating toward the east
Immediately after the collision, the man and boy are seen to be moving together at 2.5 m/s in a direction 60° north of east. How fast was the boy moving just before the collision?
If the insulating material in a wall is modified so that the R-value is increased by 50%, how will the rate of energy transferred by conduction through the wall be affected?
1.It will increase by 50%. 2.It will decrease by 50%. 3.It will increase by more than 50%. 4.It will decrease by more than 50%.
A string is stretched and fixed at both ends, 200 cm apart. If the density of the string is 0.015 g/cm, and its tension is 600 N, what is the fundamental frequency?
a. 316 Hz b. 632 Hz c. 158 Hz d. 215 Hz e. 79 Hz
An observer's nadir is
a. the point directly opposite the observer's zenith. b. the north point on the observer's horizon. c. located at the center of Earth. d. always located near a circumpolar constellation. e. directly opposite the north celestial pole.