Here's why:
* Every object with mass has a gravitational pull. The more massive an object is, the stronger its gravitational pull.
* Gravity is a force of attraction. This means that objects with mass pull on each other.
* The center of mass is the point where all the mass of an object is considered to be concentrated.
Therefore, the gravitational force between two objects acts along the line connecting their centers of mass, and it always pulls towards that center.
For example:
* You and the Earth: The gravitational force between you and the Earth pulls you towards the Earth's center of mass.
* The Moon and the Earth: The gravitational force between the Moon and the Earth pulls the Moon towards the Earth's center of mass, causing the Moon to orbit the Earth.
It's important to note that gravity is a weak force at short distances, but it has an infinite range. This means that even though gravity is weak between you and your friend, it still exists, and it's the force that keeps you both on the Earth!
