What is gravity?

 

 

Why are apples included when we talk about gravity?

1. Gravity is a force pulling together all matter (which is anything you can physically touch). 
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3. The more matter, the more gravity, so things that have a lot of matter such as planets and moons and stars pull more strongly.
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6. Mass is how we measure the amount of matter in something. The more massive something is, the more of a gravitational pull it exerts. 
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10. As we walk on the surface of the Earth, it pulls on us, and we pull back. 
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12. But since the Earth is so much more massive than we are, the pull from us is not strong enough to move the Earth, while the pull from the Earth can make us fall flat on our faces.
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14. In addition to depending on the amount of mass, gravity also depends on how far you are from something. 
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16. This is why we are stuck to the surface of the Earth instead of being pulled off into the Sun, which has many more times the gravity of the Earth.
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20. For thousands of years man has used gravity.  In early times man didn't understand why!
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22. We are not pulled off into the Sun because, while the Sun does 'push' gravity on us, the Earth's gravity is much stronger due to our being near to the Earth's centre, .."holding" us to our planet's surface. picture
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24. Earth is constantly moving in orbit around the Sun, creating a balance between the pull of gravity and our forward 'push' preventing us from falling directly into the Sun. 

       source of 2.15 and 2.17 before editing it.

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Astronaut C. Michael Foale on the ISS

International Space Station

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