. State the universal law of gravitation

The Universal Law of Gravitation states that every particle of matter in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers. This law was first stated by Sir Isaac Newton in his work "Philosophiæ Naturalis Principia Mathematica" in 1687.

Here are the steps to understand it:

1. Consider two objects in the universe, object A and object B. Each object has a mass, which we'll call m1 for object A and m2 for object B.

2. According to the Universal Law of Gravitation, these two objects attract each other with a force. This force is directly proportional to the product of their masses (m1 * m2). This means that if you increase the mass of either object, the force of attraction between them also increases.

3. The force of attraction is also inversely proportional to the square of the distance between the centers of the two objects. If we call this distance r, then the force is proportional to 1/r^2. This means that as the distance between the two objects increases, the force of attraction decreases, and it decreases very rapidly because of the square in the denominator.

4. The actual formula for the force is F = G * (m1 * m2) / r^2, where G is the gravitational constant. This constant is a very small number, which is why we don't feel the force of gravity from distant objects in our everyday lives.

5. This law applies to all objects in the universe, not just on Earth. It explains why planets orbit the sun, why the moon orbits the Earth, and why we stay grounded on Earth instead of floating off into space.