# Yr 11 Physics

## Yr 11 Physics

• Submitted By: gowymeh
• Date Submitted: 09/09/2009 12:57 AM
• Category: Science
• Words: 693
• Page: 3
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Aristarchus of Samos (around 310 – 250 BC)

Aristarchus was the first to assert a heliocentric system. Aristarchus’ original work on the heliocentric model didn’t survive, but research shows that information on Aristarchus was retrieved from Archimedes. Aristarchus’ belief was that the sun at the centre of the universe, and the outer fixed stars are motionless and the Earth and moon revolve around the sun on the circumference of a circle. Aristarchus’ heliocentric model was very much against the teachings of the church.
Aristarchus also recorded the size of the sun and moon and measured the distances of the sun and moon from Earth. The geometric methods that Aristarchus used were correct but his results were inaccurate because he had poor mathematical ability, and the inaccuracy of the equipment used.

Nicholas Copernicus (1473 – 1542)

Copernicus proposed the Copernican Model. The Copernican Model was a theory describing the structure of the universe. This theory supported Aristarchus’ heliocentric system. The Copernican Model suggested that the sun was fixed at the centre of the universe and that the Earth, the moon, and the other planets moved around the sun on circular orbits. The order of the planets from the sun was Mercury, Venus, Earth and the moon, Mars, Jupiter and Saturn. Outside this it was believed that there was a formation of fixed stars surrounding the planets. All planets moved on their own circular orbits and the moon revolved on an orbit around Earth.

Aleksandr Friedmann (1888 – 1925)

Friedmann developed two models that explained the development of the universe. He discovered one type, a closed universe. A closed universe meant that the gravitation in the universe was able to bring all matter to a stop and then repeating the cycle in reverse causing everything to contract back together. The second model was an open universe; the universe is expanding so fast that the gravity can never stop it.
1922 – 24, Friedmann used Einstein’s...