Parabolic trajectory of a projectile
On the fourth day of the Discorsi (Leiden, 1638) Galileo proved that the trajectory of a projectile launched at an angle to the horizon is a parabola. He resolved the motion into two independent components, a uniform horizontal one and a uniformly accelerated vertical one under gravity. Their sum gives the parabola.
This argument became the model of classical mechanics. Motion ceased to be a subject to argue about in Aristotelian language of 'natural places' and 'compound motions' and became a mathematically describable process. The subsequent course, through Torricelli, will turn the idea of resolution into components into the general language of physics.
Why this date
exact: Leiden, 1638, by the Elsevirs. A dialogue in four days; the fourth is devoted to the motion of projectiles.
What grew out of it
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Torricelli's ballistic tables
prerequisite for · Confidence: high
Torricelli, Galileo's assistant and his successor at court, carried on precisely the work on the parabolic motion of a projectile that Galileo published in 1638.
Link sources
- MacTutor History of Mathematics, «Evangelista Torricelli» Verified 28 Sep 2026
This basically carried on developing Galileo's study of the parabolic motion of projectiles
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- MacTutor History of Mathematics, «Evangelista Torricelli» Verified 28 Sep 2026
Node sources
- Stanford Encyclopedia of Philosophy, «Galileo», Bibliography / Primary Sources Verified 5 Oct 2026
1638, Discourses and Mathematical Demonstrations Concerning Two New Sciences (Discorsi e Dimostrazioni Matematiche intorno a Due Nuove Scienze, Leiden: Elsevier.)
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.