Answer:
The truck will roll 40.5 feet from top of the hill after 9 seconds.
Step-by-step explanation:
Let be [tex]f(t)[/tex] the distance rolled by the truck in time, measured in feet, whose expression is:
[tex]f(t) = 0.5\cdot t^{2}[/tex]
Where [tex]t[/tex] is the time, measured in seconds.
By evaluating this function at [tex]t = 9\,s[/tex], we find the distance rolled by the truck:
[tex]f(9\,s) = 0.5\cdot (9\,s)^{2}[/tex]
[tex]f(9\,s) = 40.5\,ft[/tex]
The truck will roll 40.5 feet from top of the hill after 9 seconds.