Discuss how astronomers know that our galaxy contains spiral arms in its disk
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Radio astronomers use the strong spectral line emission from carbon monoxide (CO) to map the location of giant molecular clouds in the plane of the galaxy. Giant molecular clouds are sites of active star formation. If you point a radio telescope at a section of the Milky Way, you will receive a combination of signals from gas clouds in the direction you are looking that lie at various distances across the galaxy. Signals from those different clouds can be separated by measuring the Doppler shifts of their spectral lines. Astronomers then use a simple model of orbital velocities at different distances from the center of the galaxy in order to untangle the observations and locate the individual clouds. Maps constructed from such observations reveal that the giant molecular clouds, like O and B stars, are located along segments of spiral arms.
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The critical angle for Lucite is 41.8
What is Brewster's angle for Lucite?
A. 33.7
B. 26.3
C. 48.2
D. 56.3
E. Brewster's angle does not exist for this material
In their common rest frame, two stars are 90.0 light-years (ly) apart. If they are 12.0 ly apart as measured by the navigator in a spaceship traveling between them, how fast is the spaceship moving? Express your answer in terms of c
A) 0.991c B) 0.986c C) 0.980c D) 0.972c
A car is traveling along a highway at 65 mph. What is the linear speed of the bottom of the tires?
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How many degrees of hardness are defined
on the Mohs hardness scale? a) 3 b) 7 c) 10 d) 12