Answer:
[tex]\large \boxed{\text{2.0 s}}[/tex]
Explanation:
[tex]\begin{array}{rcl}v & = & gt\\\text{20 m$\cdot$s}^{-1} & = & \text{9.807 m$\cdot$ s}^{-2} \times t\\t & = & \dfrac{20}{9.807 \text{ s}^{-1}}\\\\& = & \textbf{2.0 s}\\\end{array}\\\text{The ball is in free fall for $\large \boxed{\textbf{2.0 s}}$}[/tex]
