Aristotelian physics laws of physics". The Persian polymath Abū Rayhān al-Bīrūnī (973-1048) was the first to realize that acceleration is connected with non-uniform motion (as later expressed by Newton's second law of motion). During his debate with Avicenna, al-Biruni also criticized the Aristotelian theory of gravity firstly for denying the existence of levity or gravity in the celestial spheres; and, secondly, for its notion of circular motion being an innate property of the heavenly bodies. In 1121, al-Khazini, in "The Book of the Balance of Wisdom", proposed that the gravity and gravitational potential energy of a body varies depending on its distance
Projectile motion Projectile motion Projectile motion is a form of motion experienced by an object or particle (a projectile) that is thrown near the Earth's surface and moves along a curved path under the action of gravity only (in particular, the effects of air resistance are assumed to be negligible). This curved path was shown by Galileo to be a parabola. The study of such motions is called ballistics, and such a trajectory is a "ballistic trajectory". The only force of significance that acts on the object is gravity, which acts downward, thus imparting to the object a downward acceleration. Because of