Question 1
What was true of African building materials during the first millennium C.E.?
a. Stone was increasingly used in West Africa during in the first millennium C.E.
b. The only construction material used during that period was dried mud.
c. Mosques were always constructed of wood.
d. The heavy use of mortar was predominant in buildings constructed at Great Zimbabwe.
e. Metal became an important building material as early as 1000 B.C.E.
Question 2
The three laws of motion that govern the planetary bodies and the objects on earth were explained by
a. Isaac Newton.
b. Galileo Galilei.
c. Ptolemy.
d. Nicolaus Copernicus.
e. Johannes Kepler.
Motion of the barycenter of the Solar System relative to the Sun
Uranus's aurorae against its equatorial rings, imaged by the Hubble telescope. Unlike the auror
Scaling the Earth down to the size of a basketball, the Moon is roughly the size of a tennis ball. T
How to use the laws of exponents to simplify an expression (Part 1)
Earth’s Climate System
Relative Sizes of Dwarf Planets and Earth