The spectrum of Star A has an absorption line of hydrogen at 660.0 nm. The spectrum of Star B has an absorption line at 666 nm. The wavelength of this transition in the laboratory is 656 nm. What can I say about Star A and Star B?
A) Both stars are moving away from me, Star A is faster than Star B.
B) Both stars are moving toward me, Star A is faster than Star B.
C) Both stars are moving toward me, Star B is faster than Star A
D) Both stars are moving away from me, Star B is faster than Star A.
D) Both stars are moving away from me, Star B is faster than Star A.
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Why is there a limit to how much compression can be counterbalanced by electron degeneracy pressure?
A) At extreme compression, the electron speeds approach the speed of light and therefore cannot increase further. B) At extreme compression, electrons are forced to stop moving, and once stopped there is nothing more they can do. C) At extreme compression, atoms are fully ionized, so electrons go free and can no longer exert pressure. D) The exclusion principle excludes electrons from exerting more pressure than the uncertainty principle would otherwise allow. E) Electrons are very small and are simply incapable of exerting much pressure.
According to Einstein's equivalence principle, which of the following cannot be distinguished from a system accelerating with uniform acceleration in the presence of no gravity by any measurement within the system?
A) a system moving with constant velocity in the presence of no gravitational force B) a system that only contains massless objects C) a system that is not accelerating, but is subject to a uniform gravitational acceleration D) a system that is moving at the speed of light E) a system in free fall
Which scenario is portrayed by the graph?
A. A car starts from rest and accelerates. It then travels at a constant velocity before slowing to a stop.
B. A car starts from rest and moves forward. It stops for a while before returning to its starting position.
C. A car travels at a constant velocity, then accelerates for a while, then returns to its initial constant velocity.
At the top of the Hertzprung—Russell diagram we find
A) red giant stars B) white dwarfs C) supergiant stars D) main sequence stars