It's difficult to pinpoint a single individual as the "first discoverer" of the relation between motion and force. This understanding developed over centuries through the work of many thinkers and scientists. Here's a breakdown:

Early Insights:

* Aristotle (384-322 BC): He believed that a force was needed to keep an object in motion. He described motion as either natural (like objects falling) or violent (requiring a force). This concept was influential for over a thousand years.

* Galileo Galilei (1564-1642): Galileo, through his experiments, showed that objects in motion would continue to move at a constant speed unless acted upon by a force. This laid the groundwork for the concept of inertia.

Newton's Formulation:

* Isaac Newton (1643-1727): Newton formalized the relationship between motion and force with his Laws of Motion:

* First Law: An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. (Law of Inertia)

* Second Law: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. (F = ma)

* Third Law: For every action, there is an equal and opposite reaction.

Conclusion:

While Galileo's work was crucial in setting the stage, Newton's Laws of Motion provide the most comprehensive and mathematically precise description of the relationship between motion and force. Therefore, it's fair to say that Newton played a pivotal role in solidifying this understanding.

It's essential to remember that scientific discovery is a collaborative and iterative process. Many individuals contributed to understanding the relationship between motion and force, and Newton built upon the work of his predecessors.