The force due to gravity between two objects can be described using the equation Fg = G M1 M2 / d2. According to this equation, if the distance between two objects increases, what happens to the gravitational force between them?
A) The force increases.
B) The force decreases.
C) The force drops instantly to zero.
D) The gravitational force is not affected by distance.
Question 2What is the diameter of the galaxy, in km?
A) about 1 billion trillion km (1021 km) B) about 10 trillion km (1013 km)
C) about 1 million trillion km (1018 km) D) about 100,000 km (105 km)
Question 3Which of the following describes tectonics?
A) the excavation of bowl-shaped depressions by asteroids or comets striking a planet's surface
B) the eruption of molten rock from a planet's interior to its surface
C) the disruption of a planet's surface by internal stresses
D) the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather
Question 4One light-year is the distance light travels in one year. The speed of light is about 300,000 km/s . How far is 1 light-year?
A) 1.08 billion km (1,080,000,000, or 1.08 109 km)
B) 300 thousand km (300,000, or 3 105 km)
C) 9.46 trillion km (9,460,000,000,000, or 9.46 1012 km)
D) 18 million km (18,000,000, or 1.8 107 km)
Question 5What eventually halts the gravitational collapse of an interstellar gas cloud that forms an object that is massive enough to become a star?
A) the central object becoming hot enough to sustain nuclear fusion in its core
B) a critical fraction of the gas has been driven further into space
C) nothing; all collapsing gas clouds become black holes
D) the crowding of electrons in the core
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