Match these words with their definitions.
1. elliptical a. suppose, speculate
2. orbit b. talk or write more about something
3. expand on c. a statement describing a phenomenon in science which is true at all times
4. the heavens d. having the Sun as the centre
5. inertia e. a path around another object
6. gravity f. effect
7. geocentric g. having the Earth as the centre
8. heliocentric h. the sky
9. hypothesise i. oval or egg-shaped
10. revolve g. what makes things fall
11. law k. law of physics according to which a body tends to maintain its speed & direction
12. impact l. move around
The Law of Universal Gravitation
In ancient times, people believed that the Earth was the centre of the solar system and tried to understand and explain the movement of the Sun, the Moon, the stars and the planets around the Earth. As scientific knowledge and technology improved over time, this idea (called the geocentric theory, from the ancient Greek words meaning Earth-centred) lost favour and new theories about the solar system were put forward.
Tycho Brahe (1546-1601) and Galileo (1564-1642) made accurate measurements of the heavens, which were the basis for later theories. Nicolas Copernicus (1473-1543) believed that the Earth was not the centre of the solar system but just another planet revolving around the Sun, which itself never moved. This type of theory was called heliocentric. Johannes Kepler (1571-1630), an assistant to Brahe, used Brahe's measurements to support Copernicus' heliocentric theory. This led to his discovery of three laws relating to planetary movement, including the fact that the planets move in elliptical orbits around the Sun.
It was left to Isaac Newton to expand on these theories by testing and proving Kepler's laws. By observing things around him, Newton realised several things. One was that objects can be in one place, without moving. This is called inertia. Then, if the object moved, it moved toward another object. The phenomenon causing this pull of one object towards another was the force of gravity (or little g). Newton found that the mass of the two objects and the distance between them determined the strength of the force of gravity and developed an equation which expressed this relationship.
Continuing to test and expand his findings, Newton hypothesised that this relationship existed not only between objects on the Earth but also objects in space. This led in 1687 to Newton's Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy, usually called Principia) in which he wrote about his historic discovery of the Law of Universal Gravitation (or big G). By calling his discovery a law, it meant that the relationships he had discovered were true everywhere and in all cases.
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Newton's discovery had a huge impact on scientific thinking for centuries afterwards. In fact, his findings were not improved upon until 1905, when Albert Einstein introduced his Special Theory of Relativity.
Read the text and choose the correct title for each paragraph. There is one title which you do not need to use.
Newton's discovery
Early theories of heliocentrism
The strength of Newton's Law
Geocentrism
Newton's observations
Einstein's theories
The Law of Universal Gravitation
1. В древности считалось, что земля является центром солнечной системы, что приводило к ошибочным теориям.
2. То, что планеты двигаются по эллиптическим орбитам вокруг солнца, было объяснено гелиоцентрической теорией Коперника.
3. Иоганн Кеплер проверил и подтвердил гелиоцентрическую теорию Коперника.
4. Именно Исаак Ньютон, наблюдая за предметами, окружающими его, понял, что объекты могут находиться на одном и том же месте без движения, и назвал это явление инерцией.
5. Гравитационная сила - это притяжение одного объекта к другому. Она определяется массой двух объектов и расстоянием между ними.
6. Закон всемирного тяготения справедлив всегда и везде, не только на Земле, но и в космосе.
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7. Открытие законов гравитации оказывало огромное влияние на научную мысль в течение столетий.
Вариант 4
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