Question

A stone piece is just dropped from a height of 180m. Its velocity increase uniformly at the rate of 10m², with what velocity will it strike the ground. How much time does the stone take to reach the ground?

Answer 1

by using v^2 = u^2 + 2as
velocity = 60m/s
by using v = u + at
time = 6 sec

Answer 2

  We know that    

        s = ut + 1/2a t²

       ⇒180 = 0 + (1/2)(10)t²

       ⇒180 = 5  t²

       ⇒180/5 = t²

       ⇒36  = t²

       ⇒√36 = t

       ⇒t = 6

∴Time taken is 6 seconds