Briefly explain why radiation was trapped for 300,000 years during the era of nuclei, and why the cosmic background radiation broke free at the end of this era
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During the era of nuclei, the universe consisted of a hot plasma of hydrogen nuclei, helium nuclei, and free electrons. Throughout this era, photons bounced rapidly from one electron to the next, just as they do deep inside the Sun today, never managing to travel far between collisions. If a nucleus managed to capture an electron to form a neutral atom, one of the photons quickly ionized it. This era came to an end when the expanding universe had cooled down to about 3,000 K. At this temperature, the hydrogen and helium nuclei were able to capture electrons and form stable, neutral atoms for the first time. With electrons bound into atoms, the photons began to stream freely across the universe.
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Theories for how the universe formed, have taken which of the following into account:
In 1989, Neptune was found to have a huge storm named the:
A) South Tropical Disturbance. B) Great Red Spot. C) Great Dark Spot. D) Hellas Basin. E) Galileo Regio.
Most pulsars are observed only as ________ sources
A) X-ray B) radio C) gamma-ray burster D) visible lighthouse E) ultraviolet repeating
A force on a particle depends on position such that
F(x) = (3.00 N/m2)x2 + ( 2.00 N/m)x for a particle constrained to move along the x-axis. What work is done by this force on a particle that moves from x = 0.00 m to x = 2.00 m? A) 10.0 J B) 12.0 J C) -32.0 J D) 16.0 J E) 32.0 J