Homework 2 - 360 degrees of a circle (360 divided by 7.2...

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1LAURA SEWELL CE 2103 HOMEWORK 2 Eratosthenes was the first to “measure” the approximate circumference of the earth. The idea that he could discover the circumference of earth first started because he heard of a deep well at Syene (near the Tropic of Cancer and modern Aswan) where sunlight only struck the bottom of the well on the summer solstice. Greek scholars already knew that the earth was indeed a sphere, so in order to calculate the circumference, Eratosthenes needed two things. He knew the approximate distance between Syene and Alexandria, because it was measured by “camel-powered trade caravans”. He then measured the angle of the shadow of a stick in Alexandria on the solstice. When he took the angle of the shadow (7°12') and divided it into the
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Unformatted text preview: 360 degrees of a circle (360 divided by 7.2 gives you 50), Eratosthenes then multiplied the distance between Alexandria and Syene by 50 to determine the circumference. Eratosthenes was able to determine the circumference to be 25,000 miles, which is just 100 miles more than the actual circumference at the equator. A few decades later, the Greek geographer Posidonius thought Eratosthenes' circumference was too large. He calculated the circumference on his own and obtained 18,000 miles, 7,000 miles too short. During the middle ages, most scholars accepted Eratosthenes' circumference. In old age, Eratosthenes became blind and died of starvation around 192 or 196 B.C. and lived to be about 80 to 84 years old....
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