gravity

/Tag: gravity

What is a galaxy? – Astronomy – Space science

By |2019-06-29T09:19:08-07:00August 18th, 2017|Physics|

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 be in one or another galaxy. Earth's own star, the Sun, is in the Milky Way galaxy. What is the sun made of? What are [...]

Earthquakes and algae – the planet Earth

By |2019-05-22T14:05:38-07:00August 18th, 2017|Physics|

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 lot of heat, so the whole center of the planet Earth is made of hot melted iron. How old is the Earth? What is [...]

How old is the Earth? – Astronomy

By |2019-05-22T11:28:46-07:00August 18th, 2017|Physics|

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 half billion years ago. (That's about 4,600,000,000 years ago.) What's the sun made of? How do planets form? All our physics articles What [...]

Brown dwarf stars – Space science

By |2019-02-24T19:58:01-07:00August 17th, 2017|Physics|

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 gotten enough mass together yet to begin nuclear fusion. More about nuclear fusion Different types of stars What are stars made of? All our physics articles [...]

Black holes – Space science – Physics

By |2019-02-20T19:38:04-07:00August 17th, 2017|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 a place in space where there is a huge amount of mass in a very small area. More about space What is mass? All our physics articles Why [...]

Newton’s First Law of Motion – Physics

By |2018-05-31T11:49:24-07:00August 17th, 2017|Islam, 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 down. But to prove this was always true, you'd need calculus, which hadn't been invented yet. In the 1700s, Isaac Newton figured out [...]

Levers – Simple machines – Physics

By |2018-05-31T11:49:33-07:00August 17th, 2017|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 - a fixed object - to move something. A lever helps you move something heavy, or make something go fast. The earliest levers developed [...]

What is friction? Definition of friction

By |2019-06-17T15:26:30-07:00August 16th, 2017|Physics|

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 things, like your two hands rubbing together. A friction project Friction and food coloring Definition of inertia All our physics articles More examples [...]