Why are Cepheid variables important?
A) Cepheid variables are stars that vary in brightness because they harbor a black hole. Therefore, they provide direct evidence for black holes.
B) Cepheids variables are supermassive stars that are on the verge of becoming supernovae. Therefore they allow us to choose candidates to watch if we hope to observe a supernova.
C) Cepheids variables are a type of irregular galaxy, much more common in the early universe. Therefore they help to understand how galaxies formed.
D) Cepheids variables are pulsating stars whose pulsation periods are directly related to their true luminosities. Therefore they can be used as distance indicators.
D
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A) another First Quarter Moon B) Last Quarter C) Waxing Crescent D) New Moon E) Full Moon
While driving down the highway a lovebug spatters onto your windshield. Which undergoes the greater change in momentum during the time of contact?
A) the lovebug B) your car C) both the same
The graphs below represent current and voltage phasors at one instant of time. The solid arrows represent the voltage phasors, ?V, and the dashed arrows represent the current phasors, Imax.Which graph shows the correct relationship between current and voltage phasors for an inductor in an RL circuit?
a.
b.
c.
