sphere

/Tag: sphere

What’s the equator? Geography and the Earth

By |2019-05-30T17:06:09-07:00August 20th, 2017|Physics|

This globe shows the equator running around the widest part of the Earth. Where is the equator? The equator is an imaginary line running around the widest part of the Earth, halfway between the North Pole and the South Pole. You can't see it. Why does Earth have weather? Plate tectonics and continents What [...]

Area of a sphere – Volume of a sphere

By |2017-07-29T13:10:50-07:00July 29th, 2017|Math|

This is a sphere. A sphere is a three-dimensional circle. Or you could say that a sphere is the set of all the points that are at the same distance from the center of the sphere. In nature, centrifugal force and gravity tend to make a lot of things into spheres: soap bubbles, for instance, atoms, and planets. The radius of a sphere [...]

Checking the surface area of a sphere

By |2017-07-29T09:44:05-07:00July 29th, 2017|Math|

Did you ever have to wrap a basketball as a present? To see how the surface area of a sphere is really 4πr2, find a ball to wrap (a basketball works well). Cut some wrapping paper to fit the ball. Then you'll need to measure the circumference of the ball. You could wrap a piece of string around [...]

Who was Archimedes? Eureka!

By |2019-02-01T06:23:28-07:00July 18th, 2017|History|

Archimedes was from Syracuse, Sicily. Here you see it with Mount Etna in the background When did Archimedes live? Archimedes was born about 287 BC, so he was a little younger than Euclid. Archimedes' father was an astronomer, so he grew up knowing a lot about science and math. Who was Euclid? Greek astronomy History [...]

Math and Numbers in Ancient China

By |2018-04-25T12:09:29-07:00June 7th, 2017|China, Science|

Chinese numbers: number rods Chinese numbers People in China were using written numbers by about 1500 BC, in the Shang Dynasty. This is about two thousand years later than people began to write numbers in West Asia. It's more than a thousand years later than people began to write numbers in India. Nobody knows whether [...]