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Why does a projectile follow a curved path according to Galileo’s physics?

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A diagram of a cylindrical vessel containing gas, with a movable piston held down by a weight. Countless small dots beneath the piston represent gas particles in rapid, random motion, illustrating Bernoulli's model of gas pressure. — physics As conceived by Daniel Bernoulli in *Hydrodynamica* (1738), gases consist of numerous particles in rapid random motion. He assumed that the pressure of a gas is produced by the direct impact of the particles on the walls of the container.

According to the physics developed by Galileo Galilei, a projectile follows a curved path—specifically a parabola—because its motion is the result of two simultaneous and independent components.12

Galileo realized that a projectile undergoes:
* Inertial motion in the horizontal direction, where the object maintains a constant speed because no force is required to sustain motion once it has begun.12
* Falling motion in the vertical direction, where the object is subject to constant acceleration due to gravity.312

By mathematically combining these two independent motions, Galileo demonstrated that the resulting trajectory forms a parabolic curve. This insight was a significant departure from Aristotelian physics, which incorrectly categorized such movements as requiring a continuous, proximate cause to maintain motion. Galileo’s work in kinematics provided a foundational understanding of projectile motion that later contributed to the development of classical mechanics.21