Newton's Law of Gravitation
Earth and Space

But what is gravity?

Physics Narrative for 11-14 Supporting Physics Teaching

What is gravity?

You, or one of your pupils, might pose the question: Yes, but what is gravity? There is certainly a difference between being able to describe the gravitational force acting in a given situation and being able to account for the origins of that force in more fundamental terms.

Henry: Why do things in this room fall?

Teacher: They move closer to the middle of the planet.

Clare: Why do they move closer to the centre of the planet?

Teacher: Because gravity pulls them.

Bo: Why does gravity pull them?

Teacher: Gravity pulls all objects with mass.

Rajit: Why does gravity pull all masses?

Thinking only about teaching physics in school, it is legitimate to state that gravity just exists and is a phenomenon of the natural world. Somehow we have to break out of the But why? cycle. Posing the question: What is gravity? is rather like asking Why does the universe exist? Both are interesting questions and physicists are currently engaged in basic research in an attempt to uncover the fundamental nature of gravity and the universe, but you will need extensive study to understand the answers they are likely to give.

Newton's Law of Gravitation
is expressed by the relation F=G(m_1)(m_2)/r^2
can be used to derive Kepler's First Law
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