Question

A stone is allowed to fall from the top of a tower and covers half the height of the tower in the last second of its journey. The time taken by the stone to reach the foot of the tower is 

(1) (2 - √2)s 

(2) (2 + √2)s 

(3) 4s

(4) (2 ± √2)s.

Answer 1

Answer is (4) (2 ± √2)s

h = 1/2 gt². h/2 = 1/2 g(2t – 1) 

dividing we get

t² – 4t + 2 = 0

t = 4 ± √(16 - 8)/2 = (2 ± √2)s.