Sgr A* is believed to be the center of the Milky Way galaxy because I. it lies in the general direction of the center of the galaxy based on observations of globular clusters in the plane of the Milky Way. II. long-wavelength dust-penetrating images show it to be a region crowded with stars. III. orbits of stars around it indicate a mass several million times that of the Sun within a volume a few
light hours in size. IV. radio observations show it is a concentrated source at the center of swirling clouds of gas.
a. I & II only
b. II & III only
c. I & IV only
d. II & IV only
e. All of I, II, III, & IV
e
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Index of Refraction: Light having a wavelength in vacuum of 600 nm enters a liquid of refractive index 2.0. In this liquid, what is the wavelength of the light? (c = 3.0 × 108 m/s)
A. 1200 nm B. 600 nm C. 300 nm D. 150 nm E. 200 nm
The gravitational force between two objects can be described using the equation Fg = G M1 M2 / d2. In this equation, what does d represent?
A) the universal gravitational constant B) the density of the smaller object C) the distance between the two objects D) the diameter of the larger object
Why was Herschel's strategy for mapping our Galaxy flawed?
A) His infrared telescopes couldn't penetrate the dust clouds. B) He used globular clusters, lying above the dust in the disc. C) He relied on visual wavelengths, which are obscured by dust. D) He used radio telescopes that didn't give enough resolution. E) He assumed Earth was at the extreme edge of the Galaxy.
If you exert a force F on an object, the force which the object exerts on you will
A) depend on whether or not the object is moving. B) depend on whether or not you are moving. C) depend on your mass. D) depend on the object's mass. E) always be -F.