# An object is thrown vertically from a height of 3 m at 3 m/s. How long will it take for the object to hit the ground?

Feb 19, 2016

time = 1.6 sec

#### Explanation:

The object is thrown from a height 8m, when it reaches at ground its displacement h= - 8m, its initial upward velocity u = 3m/s
if acceleration due to gravity g is taken as -10 $m {s}^{_} 2$ then equation can be written as follows

$h = u t + \frac{1}{2.} g \cdot {t}^{2}$
Or. -8 = 3t -0.5x10x${t}^{2}$
Or $5 {t}^{2} - 3 t - 8 = 0$
Or $\left(5 t - 8\right) \left(t + 1\right) = 0$
so feasible solution is t = 8/5 = 1.6 s