Contents

- 1 What is the linear distance between Alexandria and Syene?
- 2 How did Eratosthenes measure the distance between Alexandria and Syene?
- 3 What causes the difference in the angle of shadows cast in Syene and Alexandria at noon during a summer solstice according to Eratosthenes?
- 4 What is the exact circumference of the earth?
- 5 How much of a circle is 7.2 degrees?
- 6 Who first measured the distance to the sun?
- 7 How accurate was Eratosthenes measurement?
- 8 Why did Alexandria become a major center of learning?
- 9 What was Eratosthenes experiment?
- 10 What is the contribution of Eratosthenes?
- 11 How did Eratosthenes measure the size of the Earth quizlet?
- 12 What is the shape of the shadow?
- 13 How old is our world?
- 14 What is the speed of Earth on its axis?

## What is the linear distance between Alexandria and Syene?

That the distance between Alexandria and Syene is 5000 stades.

## How did Eratosthenes measure the distance between Alexandria and Syene?

Eratosthenes then measured the angle of a shadow cast by a stick at noon on the summer solstice in Alexandria, and found it made an angle of about 7.2 degrees, or about 1/50 of a complete circle. He realized that if he knew the distance from Alexandria to Syene, he could easily calculate the circumference of Earth.

## What causes the difference in the angle of shadows cast in Syene and Alexandria at noon during a summer solstice according to Eratosthenes?

Eratosthenes reasoned that the Sun must be directly overhead at noon in Syene at this time. He knew that the Sun was not directly overhead in Alexandria on this day, so he figured that the vertical direction in Alexandria was different from the vertical direction in Syene.

## What is the exact circumference of the earth?

In 200 B.C. Eratosthenes estimated Earth’s circumference at about 46,250 kilometers (28,735 miles). Today we know our planet’s circumference is roughly 40,000 kilometers (24,850 miles).

## How much of a circle is 7.2 degrees?

Since there are 360 degrees in a circle, 7.2 degrees is 1/50 of an entire circle.

## Who first measured the distance to the sun?

Historically, the first person to measure the distance to the sun was the Greek astronomer Aristarchus around the year 250 B.C. He used the phases of the moon to measure the sizes and distances of the sun and moon. During a half moon, the three celestial bodies should form a right angle.

## How accurate was Eratosthenes measurement?

If Eratosthenes used one length for the stadion, his answer was really, really good. The Earth is about 40 thousand kilometers (about 24,860 miles) around. The measurement that Eratosthenes made might have been within about 1% of this.

## Why did Alexandria become a major center of learning?

Alexandria was a remarkable center of learning due to the blending of Greek and Oriental influences, its favorable situation and commercial resources, and the enlightened energy of some of the Macedonian Dynasty of the Ptolemies ruling over Egypt, in the final centuries BC.

## What was Eratosthenes experiment?

Eratosthenes analyzed the observations with the assumption that the earth is a sphere and the sun is very far away. The geometry of the situation is sketched at the right. He concluded that the circumference of the earth was about 50 times greater than the distance from Alexandria to Aswan.

## What is the contribution of Eratosthenes?

He is credited with devising an algorithm for finding prime numbers called the sieve of Eratosthenes, in which one arranges the natural numbers in numerical order and strikes out one, every second number following two, every third number following three, and so on, which just leaves the prime numbers.

## How did Eratosthenes measure the size of the Earth quizlet?

How did Eratosthenes measure the circumference of the Earth? He used geometry and ratios to determine the size of the Earth, by basing his calculations on observations of the sun. You just studied 5 terms!

## What is the shape of the shadow?

Shadows give us some information about shapes of objects. Sometimes shadows can also mislead us about the shape of an object If the curved surface of the cylinder is placed perpendicular to the path of the light, the shape of the shadow obtained is a rectangle.

## How old is our world?

According to data taken by 183 high-school classes participating in a World Year of Physics project, “Measure the Earth with Shadows”, the radius of Earth is 6563 km, compared to the accepted value for the mean radius of 6371 km.

## What is the speed of Earth on its axis?

The earth rotates once every 23 hours, 56 minutes and 4.09053 seconds, called the sidereal period, and its circumference is roughly 40,075 kilometers. Thus, the surface of the earth at the equator moves at a speed of 460 meters per second–or roughly 1,000 miles per hour.