According to what we now know from Newton's laws, which of the following best explains why Kepler's second law is true?
A) A planet's angular momentum must be conserved as it moves around its orbit.
B) Orbits must be elliptical in shape.
C) Gravity is an inverse cube law.
D) This effect happens because of the influence of other planets on a particular planet's orbit.
A
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At a pressure of 1 atmosphere, a mixture of two metals (A and B) has the three phases ?, ?, and ? in equilibrium. Can the temperature be changed and still have the ?, ?, and ? phases in equilibrium? _____________
Fill in the blank(s) with the appropriate word(s).
The idea that energy in atoms has distinct energy levels is part of the branch of physics that is called
A) special relativity. B) general relativity. C) quantum physics. D) classical physics. E) particle physics.
The gravitational field on the surface of the earth is 
mass of the earth is 
kg, radius of the earth is
meters)
A. 3.40 N/kg. B. 6.20 N/kg. C. 9.80 N/kg. D. 10.1 N/kg. E. 20.3 N/kg.
Determine the atomic mass of a hypothetical element that occurs on Earth as a mixture of 20.00% 32X (atomic mass of isotope = 32.00 u) and 80.00% 34X (atomic mass of isotope = 34.00 u)