Mercury has only a trace atmosphere because
A. its slow rotation allows atmospheric gases to escape the planet.
B. its close proximity to the Sun allows the Sun to gravitationally pull gases directly off the surface of Mercury.
C. impacts from planetesimals caused its original atmosphere to evaporate away.
D. its smaller size means it has gravitational attraction that is too weak to hold onto an atmosphere.
Answer: D
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Current evidence suggests that the Universe is
a. flat, infinite, and neither expanding nor contracting. b. closed, finite, and slowing its expansion. c. open, infinite, and slowing in its expansion. d. static with no expansion. e. flat, infinite, and accelerating in its expansion.
If a nucleus decays by ?+ decay to a daughter nucleus, which of the following statements about this decay are correct? (There may be more than one correct choice.)
A) The daughter nucleus has more protons than the original nucleus. B) The daughter nucleus has more neutrons than the original nucleus. C) The daughter nucleus has the same number of nucleons as the original nucleus. D) The daughter nucleus has fewer protons than the original nucleus. E) The daughter nucleus has fewer neutrons than the original nucleus.
A 3.45-kg centrifuge takes 100 s to spin up from rest to its final angular speed with constant angular acceleration
A point located 8.00 cm from the axis of rotation of the centrifuge moves with a speed of 150 m/s when the centrifuge is at full speed. (a) What is the angular acceleration (in rad/s2 ) of the centrifuge as it spins up? (b) How many revolutions does the centrifuge make as it goes from rest to its final angular speed?
The physical characteristic that is used to distinguish intrusive igneous rocks from extrusive igneous rocks is ______________
Fill in the blank(s) with correct word