Question

A stone piece is just dropped from a height of 180m.. its velocity increase uniformly at the rate of 10ms², with what velocity will it strike the ground. How much time does the stone take to reach the ground?

Answer 1

Try using formulae :
(i) v² = u² + 2.a.s   ....For finding Velocity and..

(ii) v = u + a.t  .... For finding time
 
Here, 
u=0, a=10, and s=180

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