in which the two cartesian components become completely independent, and thus easier to solve. Here, v 0 , v x and v y will be used to denote the initial velocity, the velocity along the direction of x and the velocity along the direction of y, respectively. The mass of the projectile will be denoted by m, and μ μ := k / m . For the derivation only the case where 0 o ≤ ≤ θ θ ≤ ≤ 180 o is considered. Again, the projectile is fired from the origin (0,0).