Hubble's constant is a "constant" in that its value
A) is the same across all of space and does not change on human time scales.
B) stays the same at all times.
C) is a value calculated from models, and therefore not affected by observations.
D) always stays the same unless the expansion rate is accelerating.
A) is the same across all of space and does not change on human time scales.
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The work done on an ideal gas system in an isothermal process is -400 J. What is the change in internal energy?
A) zero B) -400 J C) 400 J D) 200 J E) none of the above
A large massive rock is in contact with the earth. Draw a force diagram for the rock and the earth. Which of the following statements is true?
A. The gravitational force on the rock due to the earth and the gravitational force on the earth due to the rock are interaction partners. B. The gravitational force on the rock due to the earth and the contact force on the earth due to the rock are interaction partners. C. The contact force on the earth due to the rock and the gravitational force on the earth due to the rock are interaction partners. D. The gravitational force on the earth due to the rock and the contact force on the earth due to the rock are interaction partners.
What do we mean when we say that the Sun is in gravitational equilibrium?
A) There is a balance within the Sun between the outward push of pressure and the inward pull of gravity. B) The Sun maintains a steady temperature. C) The hydrogen gas in the Sun is balanced so that it never rises upward or falls downward. D) The Sun always has the same amount of mass, creating the same gravitational force.
A small metal sphere is suspended from the conducting cover of a conducting metal ice bucket by a non-conducting thread. The sphere is given a negative charge before the cover is placed on the bucket. The bucket is tilted by means of a non-conducting material so that the charged sphere touches the inside of the bucket. Which statement is correct?
a. The negative charge remains on the metal sphere. b. The negative charge spreads over the outside surface of the bucket and cover. c. The negative charge spreads over the inside surface of the bucket and cover. d. The negative charge spreads equally over the inside and outside surfaces of the bucket and cover. e. The negative charge spreads equally over the sphere and the inside and outside surfaces of the bucket and cover.