Based on their spin, all particles fall into which of the following categories?
A) quarks and leptons
B) fermions and bosons
C) matter and antimatter
D) color, flavor, and mass
B
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Radiation pressure: A radiometer has two square vanes (1.0 cm by 1.0 cm), attached to a light horizontal cross arm, and pivoted about a vertical axis through the center, as shown in the figure. The center of each vane is 6.0 cm from the axis. One vane is silvered and it reflects all radiant energy incident upon it. The other vane is blackened and it absorbs all incident radiant energy. Radiant energy, having an intensity of 300 W/m2, is incident normally upon the vanes. What is the radiation pressure on the blackened vane? (c = 3.0 × 108 m/s, ?0 = 4? × 10-7 T ? m/A, ?0 = 8.85 × 10-12 C2/N ? m2) 
A. 1.0 × 10-10 Pa B. 1.0 × 10-9 Pa C. 1.0 × 10-8 Pa D. 1.0 × 10-7 Pa E. 1.0 × 10-6 Pa
Which of the following is TRUE?
a) The average surface temperature of Venus is about 30 degrees Fahrenheit. b) Mercury has a very thick atmosphere made mostly of carbon dioxide. c) The runaway greenhouse effect causes the present temperatures on Mars to exceed thoseon Earth. d) Mercury rotates exactly one and a half times for every one revolution around the Sun. e) Venus has no volcanos on its surface.
Astronomers have found evidence that the expansion of the Universe is accelerating. Such acceleration
A. is deduced because distant galaxies are receding more slowly than expected from the Hubble law. B. is deduced because distant galaxies are receding faster than expected from the Hubble law. C. is deduced because nearby galaxies are receding faster than expected from the Hubble law. D. was predicted by the Big Bang model in cosmology.
Lower frequency radio waves are reflected back to earth by the ______________
Fill in the blank(s) with correct word