Answer:
A. 3s
Step-by-step explanation:
The height of the object after t seconds is given by:
[tex]h(t) = -16t^2 + 144[/tex]
When will the object hit the ground?
It hits the ground after t seconds, and t is found when [tex]h(t) = 0[/tex]. So
[tex]h(t) = -16t^2 + 144[/tex]
[tex]0 = -16t^2 + 144[/tex]
[tex]16t^2 = 144[/tex]
[tex]t^2 = \frac{144}{16}[/tex]
[tex]t^2 = 9[/tex]
[tex]t = \sqrt{9}[/tex]
[tex]t = 3[/tex]
3 seconds, so the correct answer is given by option a.
