Question

Wht is an projactile equation

Answer 1

in a two dimension projection of a projectile in to the air, from ground at an angle Ф with the horizontal and initial speed of u, the projectile follows a path.

let the origin be the point of projection.  x axis is parallel to the ground.  y axis is perpendicular to it.

x  = u cosФ t
   => t = x / (u cosФ)

y = u sinФ t  - 1/2 g t²        using the equations of motion.
     = u sinФ * x /(u cosФ)  - 1/2 * g * x² / (u² cos² Ф)

 y = x tan Ф - g x² / (2 u² cos² Ф)

this is called as the projectile equation,  which relates x with y coordinates of the projectile at any time t.