Answer:
For t=3 sec the velocity change from positive to negative
Step-by-step explanation:
we have
This is the equation of a vertical parabola open downward (the leading coefficient is negative)
where
s(t) is the distance in feet
t is the time in seconds
We know that
To find out when the velocity change from positive to negative, we need to determine the turning point of the quadratic equation
The turning point of the quadratic equation is the vertex
so
Convert the quadratic equation into vertex form
Factor -16
Complete the square
Rewrite as perfect squares
The vertex is the point (3,244)
therefore
For t=3 sec the velocity change from positive to negative