Two red stars have surface temperatures of 3000 K, but Star A's luminosity is about 5% of the Sun's and Star B's luminosity is about 32,000 times the luminosity of the Sun. How much bigger is star B than star A?
A) They are the same size.
B) Star B's radius is about 16 times larger than star A's radius.
C) Star B's radius is about 800 times larger than star A's radius.
D) Star B's radius is about 640,000 times larger than star A's radius.
E) This cannot be determined from the information given.
C
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Aluminum alloys are readily deformed into shape because they have the _________-centered-cubic crystal structure.
Fill in the blank(s) with the appropriate word(s).
According to the Bohr model, an electron in an excited state of hydrogen can emit
A) at most a single photon until the atom re-excites. B) several photons in a series of transitions to a lower state. C) a continuous stream of light. D) none of the above
A vessel containing 10 kg of water is left out where it evaporates. If the temperature remains constant at 20°C, what is the change in entropy (in kcal/K)? (The latent heat of vaporization at 20°C is 585 cal/g.)
a. 30 b. 10 c. 20 d. 40 e. 290
A 60-?C charge is held fixed at the origin and a ?20-?C charge is held fixed on the x axis at a point x = 1.0 m. If a 10-?C charge is released from rest at a point x = 40 cm, what is its kinetic energy the instant it passes the point x = 70 cm?
a. 9.8 J b. 7.8 J c. 8.8 J d. 6.9 J e. 2.8 J