What is gravity? Physics
What is gravity? The Moon orbiting Earth (taken from space) - NASA What does gravity do? Gravity attracts all objects towards each other. Gravity has been around since the very [...]
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What is a galaxy? – Astronomy – Space science
The galaxy M 100, seen through the Hubble telescope What is a galaxy? A galaxy is a group of millions of stars that are relatively near each other. Most stars seem to [...]
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08, 2017
Earthquakes and algae – the planet Earth
Molten lava: the beginnings of planet Earth What is the Earth made of? Most of the molecules that smashed together to make the Earth were iron. The smashing together released a [...]
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08, 2017
How old is the Earth? – Astronomy
Earth from space: How old is the Earth? When did the Earth form? Like Mercury and Venus and the other planets that go around the Sun, the Earth probably formed a little more than four and a [...]
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Brown dwarf stars – Space science
What a brown dwarf might look like up close What is a brown dwarf star? The very beginning of a star forming is a brown dwarf: a star that hasn't [...]
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08, 2017
Black holes – Space science – Physics
A starry sky with the Milky Way galaxy (thanks to Bernd Nies) - there are probably black holes in there somewhere! What is a black hole? A black hole is [...]
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08, 2017
Newton’s First Law of Motion – Physics
Isaac Newton, mathematician and physicist About 1000 AD, in the Islamic Empire, Ibn Sina came up with the idea that an object moving in a vacuum would just keep moving forever without slowing [...]
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Acceleration – Physics definitions
Pedaling will make her accelerate. So will going downhill. Acceleration is a way to measure how fast something is speeding up. Suppose you are riding your bike. You start out [...]
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08, 2017
Levers – Simple machines – Physics
Levers: An orangutan child using a stick as a lever What is a lever? A lever is basically just a long stick that you push or pull against a fulcrum [...]
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08, 2017
What is friction? Definition of friction
Definition of friction: Hands rubbing together is a kind of friction Definition of friction Friction is what happens when any two things rub against each other. These can be solid [...]
