THE FUNDAMENTALS OF PHYSICS

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THE NATURE OF

GRAVITY

What goes up must come down... But why that’s the case is a mystery that

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here are four fundamental forces

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tendency of motion towards the centre

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The great 7th-century Indian

mathematician Brahmagupta briefly

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did the Islamic scholar al-Biruni 300

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The first cracks appeared with the

transformation of the Solar System by

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what would happen if you tied

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and would speed up the lighter one

• but the light weight should slow
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  didn’t drop weights off the Leaning
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experiment with pendulums that

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balls down sloping channels to

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But it was Isaac Newton who

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It’s not clear whether he was truly

inspired to do t his by seeing a n apple

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described how the fall of an apple

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apple always descend perpendicularly

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that the apple is pulled by a ‘drawing

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New ton made t he leap of proposing

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the same force throughout the

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responsible for keeping the planets 5

“Newton realised

gravity was

responsible for

keeping the planets

in their orbits,

stopping them from

flying off in a

straight line”