Question 1139766
.
<pre>

h(t) = {{{-4.9*t^2 + 44.1}}}


The object will hit the ground exactly and precisely at the time moment "t", when  h(t) = 0,  or, equivalently,


    {{{-4.9*t^2 + 44.1}}} = 0.


Simplify and solve for "t" :


    {{{t^2}}} = {{{44.1/4.9}}} = 9

    t = {{{sqrt(9) .}}} = 3.


<U>ANSWER</U>.  In 3 seconds.
</pre>


Solved.


----------------


Do not forget to post your "Thanks" to me.