Question

a stone dropped from a tree take 2 sec to reach the ground find its velocity on striking the ground

Answer 1

v = u + at
v = 0 + (9.8 m/s² × 3 s)
v = 29.4 m/s

∴ Velocity of stone when it strikes the ground is 29.4 m/s

Answer 2

By first kinematical equation,
v = u + at
here, u = 0, and a = g = 9.8 m/s.
So, v = 0 + (9.8)(2)
i .e. v = 19.6 m/ s