an object dropped from cliff falls with a constant acceleration of 10m/s2 find its speed after 2s after it was dropprd

We have,
initial velocity, u = 0 m/s
acceleration. a = 10 m/s​²
final velocity, v = ?
time, t = 2 sec
$$\begin{gathered} v = u + at \\ = 0 + \left(10\right) \times 2 \\ = 20 \mathrm{m}/\mathrm{s} \end{gathered}$$

So, after 2 sec, its velocity is 20 m/s.