____ occurs when most of the material collapsing to form a protostar has fallen into a disk around the star and a strong wind from the warm protostar ejects material from its poles
a. An emission nebula
b. Hydrostatic equilibrium
c. The proton-proton chain
d. The thermonuclear fusion of hydrogen
e. A bipolar outflow
E
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The speed of light is 300,000 km/s. How far is a light-year? Be sure to show all work clearly on your calculations.
What will be an ideal response?
Two stars both have parallaxes of 0.023", but star A has apparent magnitude +2.3, while star B is magnitude +7.3. Which statement is true?
A) Star B must be ten times more luminous. B) Star A is both 100× brighter and larger than star B. C) Star A is both 100× brighter and more luminous than star B. D) Star A must be ten times closer. E) Nothing, since we do not know their absolute magnitudes.
A pure sample of 226Ra contains 2.3 × 10^13 atoms of the isotope. If the half-life of 226Ra = 1.6 × 10^3 years, what is the activity of this sample?
a. 1.4E+10 decays/yr b. 1.0E+10 decays/yr c. 3.2E+2 decays/yr d. 3.7E+16 decays/yr e. 6.2E+6 decays/yr
How wide must a narrow slit be if the first diffraction minimum occurs at ±12° with laser light of 633 nm?
a. 3.0 × 10^?6 m b. 3.0 × 10^?5 m c. 6.1 × 10^?6 m d. 6 .1× 10?5 m e. 1.5 × 10^?6 m