What key event happened during the decoupling epoch?
A) Pairs of neutrons and protons were created.
B) Electrons and positrons were created.
C) Expansion cooled the universe enough that protons could capture electrons in orbit.
D) Dark energy accelerated the cosmos on to infinity.
E) The universe underwent a brief period of very rapid expansion.
C
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How do terrestrial and giant planets differ? List as many ways as you can think of.
A person throws a ball horizontally from the top of a building that is 24.0 m above the ground level. The ball lands 100 m down range from the base of the building. What was the initial velocity of the ball? Neglect air resistance and use g = 9
81 m/s2. A) 202 m/s B) 9.80 m/s C) 19.6 m/s D) 45.2 m/s E) 94.4°
Consider a point on a bicycle wheel as the wheel turns about a fixed axis, neither speeding up nor slowing down. Compare the linear and angular velocities of the point
a. Both are constant. c. Only the linear velocity is constant. b. Only the angular velocity is constant. d. Neither is constant.
The ____________ of a black hole is the radius from a black hole at which the escape velocity is approximately equal to the speed of light
a. Roche limit b. Lagrangian point c. Chandraskhar limit d. Hubble radius e. event horizon