Use maths
For a drop from rest, ignoring air resistance, distance \(h\) after time \(t\) is:
\[
h = \frac{1}{2}gt^2
\]
On Earth, \(g \approx 9.8\,\mathrm{m/s^2}\). After \(2\,\mathrm{s}\),
\(h \approx 19.6\,\mathrm{m}\).
Why doesn't mass appear?
Gravity and inertia increase together with mass, so mass cancels out.
Without air resistance, all objects fall at the same rate.