Answer to Question #279382 in Classical Mechanics for FAO

Question

A stone has a mass of 5kg. If it takes the stone 4 sec to fall freely to the ground, calculate it's initial height above the ground, and the force with which the stone hit the ground.

Answer 1

$\begin{array}{l} m=5 kg \\ t=4 sec \\ h=\frac{g t^{2}}{2}=\frac{9,81 \cdot 4^{2}}{2}=78,48 m \\ F=m \cdot a \\ a=g \cdot t=9,81 \cdot 4=36,72 m / s ^{2} \\ F=36,72 \cdot 5=183,6 N \end{array}$