Describe what occurred during the period of decoupling
What will be an ideal response?
During decoupling, about 400,000 years after the Big Bang, the temperature was finally low enough (about 3,000 K) for neutral atoms to form. Before then, the universe was largely opaque to radiation since photons regularly scattered off of free electrons. When atoms formed, only photons of specific wavelengths would interact with matter, making the universe transparent to the cosmic background radiation.
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A 1.0-kg block is pushed up a rough 22° inclined plane by a force of 7.0 N acting parallel to the incline. The acceleration of the block is 1.4 m/s2 up the incline. Determine the magnitude of the force of friction acting on the block.
A. 1.9 N B. 2.2 N C. 1.3 N D. 1.6 N E. 3.3 N
A 25-newton weight falls freely from the rest from the roof of a building, what is the total distance the weight falls in the first 1.0 second?
A high-diver of mass 70.0 kg jumps off a board 10.0 m above the water. If, two seconds after entering the water, his downward motion is stopped, what average upward force did the water exert on him?
What will be an ideal response?
What will occur when the full moon is on the ecliptic?
A) a total lunar eclipse B) a total solar eclipse C) a partial lunar eclipse if the Moon is at perigee D) an annular lunar eclipse E) a partial solar eclipse