Which of the following is TRUE?
A) The center of the universe is located at a point about 200 Mpc from us in the center of a cluster of galaxies.
B) At the time that the Big Bang expansion began, all matter and energy in our observable universe was compressed into a single point of space.
C) It is possible for galaxies that are very distant to actually move through space at a speed several times the speed of light.
D) A redshift occurs when a photon loses energy and slows down as it moves through space.
E) We measure a redshift for roughly half of the galaxies that we observe, and for the others we measure a blueshift
Ans: B) At the time that the Big Bang expansion began, all matter and energy in our observable universe was compressed into a single point of space.
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A rock is thrown upward with a speed of 15 m/s on the surface of planet X where the acceleration of objects in free fall is 2.5 m/s2 and there is no atmosphere. How long does it take for the rock to return to where it was thrown?
A) 6.0 s B) 8.0 s C) 10 s D) 12 s
The mass of an electron and its antiparticle, a positron, is 0.511 MeV/c2 . In order to produce an electron-positron pair, a gamma ray must have an energy larger than 1.022 MeV because __________
Fill in the blank(s) with correct word
Which force, exerted between an electron and a proton, is the strongest on scales much larger than an atomic nucleus?
A) strong B) weak C) electromagnetic D) gravity E) They are all equal.
A 1.2-kg object moving with a speed of 8.0 m/s collides perpendicularly with a wall and emerges with a speed of 6.0 m/s in the opposite direction. If the object is in contact with the wall for 2.0 ms, what is the magnitude of the average force on the object by the wall?
a. 9.8 kN b. 8.4 kN c. 7.7 kN d. 9.1 kN e. 1.2 kN