The rotation curve method works:
A) only for galaxies near enough to be well resolved.
B) only for distant spiral galaxies.
C) only for elliptical galaxies.
D) for all galaxies, irrespective of their distance from Earth.
A
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Imagine we've discovered a planet orbiting another star at an average distance of 1 AU with an orbital period of 6 months. The planet has a moon that orbits the planet at the same distance as our Moon, but it takes 2 months to complete an orbit. What can we infer about this planet?
A) It is more massive than Earth. B) It is less massive than Earth. C) It has the same mass as Earth. D) We cannot answer the question without knowing the mass of the star. E) We cannot answer the question without knowing the mass of the moon.
Photon Energy: Gamma rays are photons with very high energy. How many visible-light photons with a wavelength of 500 nm would you need to equal the energy of a gamma-ray photon with energy 4.1 × 10-13 J?
A. 1.0 × 106 B. 1.4 × 108 C. 6.2 × 109 D. 3.9 × 103
If a proton inside the nucleus of an atom suddenly turned into a neutron, while the atom retained its original number of electrons, what properties of the atom would change?
A) only its atomic number B) only its atomic mass number C) only its electrical charge D) both its atomic number and atomic mass number, but not its electrical charge E) both its atomic number and electrical charge, but not its atomic mass number
Which of the following is NOT one of Hubble's types of galaxies?
A) normal spirals B) irregular type II C) dwarf ellipticals D) barrel spirals E) Seyfert spirals