$h\left(t\right)=-16t^2+b$

The function $h$ estimates an object’s height, in feet, above the ground $t$ seconds after the object is dropped, where $b$ is a constant. The function estimates that the object is $\mathrm{3,364}$ feet above the ground when it is dropped at $t=0$. Approximately how many seconds after being dropped does the function estimate the object will hit the ground?