Here's why:
* Gravity is a fundamental force: It's one of the four fundamental forces in the universe, along with electromagnetism, the strong nuclear force, and the weak nuclear force.
* Mass creates gravity: The more mass an object has, the stronger its gravitational pull. Earth has a lot of mass, so it has a strong gravitational pull.
* Attraction between objects: Gravity attracts any two objects with mass towards each other. The apple falls to the ground because of the gravitational attraction between the apple and Earth.
Let me know if you'd like to learn more about gravity!
