The lookback time of the cosmological horizon is

A) the Big Bang.
B) the age of the universe.
C) 1 billion years.
D) 10 billion years.


B

Physics & Space Science

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A 3.00 kg mass is located at x = 2.0 cm and y = -4.0 cm. A 3.00 kg mass is located at x = -5.0 cm and y = 2.0 cm. A 4.00 kg mass is located at x = -3.0 cm and y = -3.0 cm. Where is the location of the center of mass (x, y)?

A. (-0.10 cm, -0.50 cm) B. (-2.1 cm, -1.8 cm) C. (+2.1 cm, -1.8 cm) D. (-2.1 cm, +1.8 cm) E. (+1.1 cm, -2.0 cm)

Physics & Space Science

A satellite is in a circular orbit about the Earth at an altitude at which air resistance is negligible. Which of the following statements is true?

A. There is only one force acting on the satellite. B. There are two forces acting on the satellite, and their resultant is zero. C. There are two forces acting on the satellite, and their resultant is not zero. D. There are three forces acting on the satellite. E. None of the preceding statements are correct.

Physics & Space Science

With molar quantity and temperature held constant, by what factor does the pressure of an ideal gas change when the volume is five times bigger?

a. 1/5 b. 1 c. 5 d. 25

Physics & Space Science

How many 2d electron states can an atom have?

A) 8 B) 0 C) 4 D) 10 E) 6

Physics & Space Science