The equation used to represent the height of the projectile above the ground after t seconds is expressed as
h = -16t^2 + 608t.
The equation is a quadratic equation. The plot of this equation on a graph would give a parabola whose vertex would be equal to the maximum height travelled by the projectile.
The vertex of the parabola is calculated as follows,
Vertex = -b/2a
From the equation,
a = -16
b = 608
Vertex = - - 608/32= 19
So the projectile will attain maximum height at 19 seconds.
