Upto ordinary heights, the change in the distance of a projectile from the centre of the Earth is negligible small, as compared to the radius of the Earth. Due to it, the projectile moves under a uniform gravitational force and its path is parabolic, the gravitational force decrease, which is inversely proportinal to the square of the distance of the projectile from the centre of the Earth. Under such a variable force, the path of projectile is elliptical.
