In the late 1990's, it was announced that the expansion of the Universe is accelerating. What does this imply from the perspective of the big bang?
a. A force exists that we knew nothing about that causes the acceleration.
b. The Universe must be closed.
c. The Universe is finite.
d. The amount of dark matter must be greatly less than the amount of normal matter.
e. The Universe must be infinitely old.
a
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Center of Mass: The center of mass (or center of gravity) of a two-particle system is at the origin. One particle is located at (3.0 m, 0.0 m) and has a mass of 2.0 kg. The other particle has a mass of 3.0 kg. What is the location of the 3.0-kg particle?
A. (-3.0 m, 0.0 m) B. (-2.0 m, 0.0 m) C. (2.0 m, 0.0 m) D. (3.0 m, 0.0 m)
What happens when the electron in a hydrogen atom flips its direction of spin, from parallel to anti parallel to that of the proton?
A. Nothing, this transition never occurs. B. The atom emits high-energy ultraviolet rays. C. The atom emits 656-nm radiation that gives red color. D. The atom emits 21-cm radio radiation.
Which of the following critical features of the heliocentric model leads to Venus exhibiting a full range of phases?
A) When Venus is closer to the Sun, it moves faster. B) Venus passes on the far-side of the sun from the Earth's perspective. C) Venus physically distorts from a sphere as it orbits the sun.
A solenoid having N turns and carrying a current of 2.000 A has a length of 34.00 cm. If the magnitude of the magnetic field generated at the center of the solenoid is 9.000 mT, what is the value of N? (?0 = 4? × 10-7 T • m/
A) A) 860.0 B) 1591 C) 2318 D) 3183 E) 1218