How do we determine the velocities of far away galaxies, in order to use Hubble's law?
A: We measure how fast they are rotating.
B: We measure the redshifts in their spectra.
C: We determine their distances and divide by the time it takes their light to reach us.
D: We look at how flattened they are, since moving at higher velocity tends to spread a galaxy out thinner.
E: We can tell by how big they look in the sky.
Ans: B: We measure the redshifts in their spectra.
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A container of water is placed on a scale, and the scale reads 120. g. Now a 20.0g piece of copper (specific gravity = 8.90 ) is suspended from a thread and lowered into the water, not touching the bottom of the container
What will the scale now read? A) 140 g B) 120 g C) 138 g D) 122 g E) 112 g
Shepherd satellites are defined as
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In a hydrogen atom, a transition from the third to the second energy level will produce:
A) a red emission line. B) a blue green absorption line. C) a violet emission line. D) an infrared emission line. E) an ultraviolet absorption line.
What does the prefix micro- stand for?
What will be an ideal response?