The actual matter density of the universe, accounting for all of the luminous matter and all of the dark matter known to exist in galaxies and clusters, is what fraction of the critical density?
A) 25 percent B) 10 percent C) 200 percent D) 1 percent E) 100 percent
A
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Answer the following statement true (T) or false (F)
Since LF,ice = 333 J/g, what is the change in entropy (in cal/K) when 1.00 kg of ice melts?
a. 144 b. 291 c. 312 d. 516 e. 80
A semiconductor is produced by doping Group IV silicon with 1023 atoms per cubic meter of Group III gallium. Assume that at room temperature this semiconductor is in the extrinsic range of operation.
(a) What type of semiconductor is this? (b) Calculate the room-temperature electrical conductivity of this semiconductor. (c) Clearly state any assumptions you made in calculating the electrical conductivity in part (b).
If a single force acts on a moving object
A. the momentum of the object will change only if the force is in the same direction as the velocity of the object. B. the momentum of the object can only change direction, not magnitude. C. the momentum of the object must change. D. the momentum of the object can only change magnitude, not direction.