Horizontal component of velocity is constant in overall it's path and it is V₀/2.

due to height change vertical componet of velocity is change all time in it's path  so the resultant velocity is change all time in it's path. velocity becomes vertical at two points and at that point  ' a =  {g² + (5V₀²)/(8h) }^1/2

At one point acc is +ve and other point acc is -ve.

this is  a good question.