Projectile motion is a two-dimensional motion. Let the initial velocity is v0 at time t = 0, the x and y component of velocities of v0 is (v)0 and ( vy )0 at t = 0.
Here ay = -g and ax= 0 (there is no x component of gravity)
Thus, ( v x )0 remains constant throughout the projectile motion.
V x = (vx)0
vy = (vy) 0 –gt
x = x0 +(vx)0 t
y = y0 +(vy)0 t -1 /2 gt2
v2y = (v y)20 – 2g (y – y0)
If initially there is no x0 and y0, i.e., x0= 0, y0 = 0 we start from origin 0 .