How did Isaac Newton build on Galileo Galilei’s discoveries?

Isaac Newton built upon the foundational discoveries of Galileo Galilei to develop his comprehensive system of classical mechanics and universal gravitation. Newton’s work integrated Galileo’s experimental insights into a unified mathematical framework that explained motion both on Earth and in the heavens.123

Key contributions from Galileo that Newton utilized include:

• The Law of Inertia: Galileo’s experiments with inclined planes led him to deduce that a body in motion tends to remain in motion unless acted upon by an external force. Newton adopted this as his first law of motion, replacing the outdated Aristotelian view that motion required a constant, proximate cause.14
• Study of Falling Bodies: Galileo discovered that falling objects undergo uniform acceleration independent of their mass. Newton incorporated these findings into his broader theory of gravity, demonstrating that the same force causing objects to fall on Earth also governs the motion of celestial bodies.132
• Projectile Motion: Galileo identified that the path of a projectile is a parabola, resulting from the combination of independent horizontal and vertical motions. Newton’s synthesis accounted for these observations within his laws of motion and force.15

By combining Galileo’s work on kinematics with Johannes Kepler’s laws of planetary motion, Newton established a coherent, universal view of the physical universe.12