The _____ is a measure of the rate of expansion of the Universe
A) Hubble constant
B) Stefan-Boltzmann constant
C) Boltzmann constant
D) Planck constant
A
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Which of the following statements about the rings of the four jovian planets is not true?
A) All rings lie within their planet's Roche zone. B) All the particle orbits are fairly circular, near their planet's equatorial plane. C) All have gaps and ringlets, probably due to gap moons, shepherd moons, and orbital resonances. D) All probably look much like they did when the solar system first formed. E) All are made of individual particles of rock or ice that orbit in accord with Kepler's laws: inner ring particles orbiting faster, and outer ring particles orbiting slower.
In a region of space where the magnetic field of the Earth has a magnitude of 80 ?T and is directed 30° below the horizontal, a 50-cm length of wire oriented horizontally along an east-west direction is moved horizontally to the south with a speed of 20 m/s. What is the magnitude of the induced potential difference between the ends of this wire?
a. 0.45 mV b. 0.35 mV c. 0.30 mV d. 0.40 mV e. 0.69 mV
How is the Moon's mantle different from Earth's?
A. The lunar mantle is too cold to form convection cells. B. The lunar mantle extends to the center of the Moon. C. The Moon's mantle has a higher density than Earth's. D. The lunar mantle has a different composition than Earth's.
Which of the following statements describes the ecliptic?
A. the extension of Earth's equator on the celestial sphere B. the apparent path of the Sun across the celestial sphere C. the path of the Moon on the celestial sphere D. the extension of Earth's path on the celestial sphere E. The extension of Earth's equator on the celestial sphere and the apparent path of the Sun across the celestial sphere are correct.