Explain how Eratosthenes used the rays of the Sun to estimate the circumference of Earth and to demonstrate that the planet was spherical
Eratosthenes read about a well in Syene where sunlight reached the bottom at noon on the summer solstice, meaning that the Sun's rays were perfectly vertical. He measured the angle of a shadow cast by a column in Alexandria on the summer solstice, and used this angle to calculate the distance between the two cities, as a fraction of Earth's circumference. As the distance was already known, he could solve for the total circumference of Earth.
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If you wanted to study the various shapes of different kinds of bacteria, you could use
A. a light microscope or an electron microscope. B. an electron microscope, but not a light microscope. C. the unaided eye. D. a light microscope or the unaided eye.
When rivers flow over a fairly uniform substrate with a uniform initial slope, they usually develop what type of drainage pattern?
a. Arc-shaped network b. Perpendicular network c. Dendritic network d. Parallel network
Name three bodies in the solar system other than Earth that exhibit active volcanism
What will be an ideal response?
A portion of the continental crust may move upward after a period of significant erosion to maintain balance through the process of ________.
A. lithification B. volcanism C. sedimentation D. metamorphism E. isostatic adjustment