What is meant by "dark energy"?
A) the energy associated with dark matter through E=mc2
B) any unknown force that opposes gravity
C) the repulsive agent causing the universal expansion to accelerate
D) highly energetic particles that are believed to constitute dark matter
E) the total energy in the Universe after the Big Bang but before the first stars
C
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Which of the following properties can be inferred from the star's orbital period?
What will be an ideal response?
The Sun rotates now with a rotation speed of about 2 km/sec. If its radius shrank to the size of Earth, about how fast would it spin?
A. 20 km/sec. B. 400 km/sec. C. 2,000 km/sec. D. 0.2 km/sec. E. 200 km/sec.
Why can studies of carbon isotopes be used to detect the presence of past biological activity in rocks?
A) living organisms absorb only the most common carbon isotope B) living organisms remove all carbon from rocks C) living organisms absorb certain carbon isotopes more easily than others D) carbon isotopes are found only in living organisms
A point charge of 3.0 ?C is located on the y-axis at y = 4.0 m, and another point charge of 6.0 ?C is located on the x-axis at x = 5.0 m. What is the direction (ccw from x axis) of the electric field at (5.0 m, 4.0 m)?
A. 72
B. 18
C. 25
D. 53
E. 34