In the context of stellar astronomy, briefly describe dark matter
What will be an ideal response?
According to the modern studies, is clear that significant extra mass lies in the galaxy's halo, extending up to 10 times farther than the edge of the visible disk and containing up to two trillion (2 x 1012 ) solar masses. Some small fraction of this mass is made up of low-luminosity stars and white dwarfs, but most of the matter is not producing any light. Astronomers call it dark matter and conclude that it must be some as yet unknown form of matter.
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An object starts from rest with an acceleration of 2.0 
for 3.0 seconds. It then reduces its acceleration to 1.0 m/s2 for 5.0 additional seconds. The velocity at the end of the 5.0 seconds interval is
A. 6.0 m/s. B. 18 m/s. C. 8.0 m/s. D. 18 m/s. E. 11 m/s.
So far, beyond the solar system the exoplanets found have been mostly:
A) large jovians orbiting solar-type stars about where our jovians are found. B) large jovians with terrestrial-type orbits. C) terrestrials very close to their star, and transiting its disk. D) terrestrials with very elongated, distant orbits like comets. E) brown dwarfs much more massive than Jupiter.
What is the kinetic energy of an electron that passes undeviated through perpendicular electric and magnetic fields if E = 4.0 kV/m and B = 8.0 mT?
a. 0.65 eV b. 0.71 eV c. 0.84 eV d. 0.54 eV e. 1.4 eV
Solutions are
a. homogeneous mixtures. b. heterogeneous mixtures. c. nonuniform mixtures. d. none of these.