Which of the following are the best candidates to search for planets that might harbor extraterrestrial life?
A) low mass stars (less than one-tenth of the mass of the Sun), because these are the most common stars in our galaxy
B) solar-mass stars, because they have both a large habitable zone and a long stellar lifetime.
C) massive stars (greater than twice the mass of the Sun) because they provide more energy to promote biology
D) halo stars, because planets can form in isolation from disruptive stellar encounters
E) binary stars, because they provide twice as much energy to promote biology
B
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The first successful attempt to establish the size of the earth is credited to ________.
Series Resonance: A series circuit consists of a 0.440-H inductor, a 380.0-? resistor, a 5.70-?F capacitor, and an ac voltage source of amplitude 250.0 V. Find the rms voltage across the capacitor when the circuit operates at resonance.
Fill in the blank(s) with the appropriate word(s).
During a snowball fight, two balls with masses of 0.4 and 0.6 kg, respectively, are thrown in such a manner that they meet head-on and combine to form a single mass. The magnitude of initial velocity for each is 20 m/s. What is the speed of the 1.0-kg mass immediately after collision?
a. zero c. 4 m/s b. 3 m/s d. 5 m/s
What is Einstein's cosmological constant?
A) the value of the expansion rate of the universe B) the value of the acceleration of the universe C) the value that measures the strength of gravity across the universe D) the size of the cosmological horizon E) a repulsive force that counteracts gravity and was introduced to allow for a static universe