The height of the object is given by:
[tex]h(t)=-16t^2+141[/tex]to know when will it hit the ground we equate the expression to zero and solve for t:
[tex]\begin{gathered} -16t^2+141=0 \\ 16t^2=141 \\ t^2=\frac{141}{16} \\ t=\pm\sqrt[]{\frac{141}{16}} \\ t=\pm\frac{\sqrt[]{141}}{4} \end{gathered}[/tex]Since time has to be positive it takes:
[tex]\frac{\sqrt[]{141}}{4}\text{ seconds}[/tex]for the object to hit the ground. This is approximately 2.97 seconds.
