When a massive star begins to run out of hydrogen to fuse, its core ________.
A. expands and cools
B. expands and heats
C. contracts and cools
D. contracts and heats
Answer: D
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A doubly charged ion with speed 6.9 × 106 m/s enters a uniform 0.80-T magnetic field, traveling perpendicular to the field. Once in the field, it moves in a circular arc of radius 30 cm
What is the mass of this ion? (e = 1.60 × 10-19 C) A) 3.3 × 10-27 kg B) 6.7 × 10-27 kg C) 8.2 × 10-27 kg D) 11 × 10-27 kg
In a flat Universe the angles of a triangle add up to ________.
A. exactly 360 degrees B. less than 180 degrees C. exactly 180 degrees
Open spaces in ice crystals contribute to
A) decreased density. B) increased density. C) neither of these