The average orbital speed of a star around the center of our galaxy depends primarily on
A) the mass of the Milky Way's central black hole.
B) the mass of the entire galaxy, including the halo.
C) whether the star is in the disk or halo of the galaxy.
D) the mass of the galaxy inside its orbit.
D) the mass of the galaxy inside its orbit.
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A solenoid of inductance L = 50 mH has a magnetic energy U = 3 x 10-4 J with a density u = 0.0042 J/ m3. What is the winding density n of the solenoid?
A) 58 turns/m B) 1584 turns/m C) 1200 turns/m D) 234 turns/m E) 746 turns/m
The resolving power of a telescope is
a. a measure of the minimum angular separation that can be seen with the telescope. b. a measure of the maximum angular separation that can be seen with the telescope. c. a measure of the amount of light that the telescope can gather in one second. d. the separation between the objective and the image. e. a measure of how blurry object appear in the telescope.
A charged particle (mass = M, charge = Q > 0) moves in a region of space where the magnetic field has a constant magnitude of B and a downward direction. What is the magnetic force on the particle at an instant when it is moving horizontally toward the north with a speed V?
a. QVB toward the east b. Zero c. QVB toward the west d. QVB upward e. QVB toward the south
A lens that is thicker at the center than at the edge is
a. a diverging lens only. b. a convex lens only. c. a converging lens only. d. both a convex lens and a converging lens.