What is Free fall?

Example 26.4 (Orders of magnitude)

After $1$, $2$, $3$ seconds of free fall: $v = 9.8$, $19.6$, $29.4\,\mathrm{m}/\mathrm{s}$ ($35$, $71$, $106\,\mathrm{km}/\mathrm{h}$) and $h = 4.9$, $19.6$, $44.1\,\mathrm{m}$. From a $30\,\mathrm{m}$ rooftop: $t = \sqrt{2h/g} \approx 2.5\,\mathrm{s}$, arriving at $24\,\mathrm{m}/\mathrm{s}$ $\approx 87\,\mathrm{km}/\mathrm{h}$. Times grow like $\sqrt h$ — and past a few seconds the air refuses to stay negligible (last section).