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Space Travel

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Scientists use what they know about forces and motion

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when they send rockets into space

Gravity pulls things toward Earth

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In order to lift rockets into space,

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powerful engines are needed

The force of the rocket engines must be greater

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than the force of gravity which is

9.8 meters/second/second

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In that way the rockets can escape Earth’s powerful pull

Some rockets carry satellites

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Vocabulary:

satellites

an object that orbits, or moves around , Earth

Once a satellite is in space,

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the force from its engine balances the force from Earth’s

gravity

Then the satellite circles Earth

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the way the moon circles Earth

Some satellites are put into space to study the weather on

Earth

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Other satellites send radio and television signals around the

world

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Some rockets explore other planets a

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and their natural satellites, or moons