What changed Newton's original work on the movement of the Moon around the Earth into the law of universal gravitation?

1) his conclusion that the same laws applied to all objects, no matter how small

2) his connection of gravitation to his first law

3) his connection of gravitation to Kepler's observations of planetary movement

4) his conclusion that planets move in elliptical orbits around the Sun

5) his conclusion that the same laws applied to all heavenly bodies, not just the Earth and the Moon

The answer is 3) his connection of gravitation to Kepler's observations of planetary movement.

To understand how Newton's original work on the movement of the Moon around the Earth was changed into the law of universal gravitation, we can follow these steps:

1) Newton initially focused on understanding the motion of objects on Earth, which led to his three laws of motion. These laws provided a framework for understanding how objects move under the influence of forces.

2) At the same time, Johannes Kepler, through his careful observations of planetary motion, had discovered three empirical laws known as Kepler's laws of planetary motion. These laws described the motion of planets around the Sun.

3) Newton realized that his laws of motion could be used to explain Kepler's laws of planetary motion. He connected the concept of gravitation, which is a force that pulls objects towards each other, to his first law of motion. This connection allowed him to interpret Kepler's laws as consequences of a universal gravitational force.

4) By making this connection, Newton was able to generalize his understanding of motion and apply it not just to objects on Earth but also to celestial bodies like the Moon, planets, and other heavenly bodies.

5) Newton's conclusion that the same laws applied to all heavenly bodies, not just the Earth and the Moon, was a significant change from his original focus on Earthly motion. This insight led to the formulation of the law of universal gravitation, which 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 them.

Therefore, Newton's connection of gravitation to Kepler's observations of planetary movement was the key factor that changed his original work on the Moon's movement into the law of universal gravitation.

The answer is option 3) his connection of gravitation to Kepler's observations of planetary movement. Newton's original work on the movement of the Moon around the Earth evolved into the law of universal gravitation when he made the connection between gravitation and Johannes Kepler's observations of planetary movement. This connection allowed Newton to generalize his findings and propose that the same principles applied not only to the Moon and Earth but also to other celestial bodies.