Q2. A body projected vertically upwards with a certain speed from the top of a tower reaches the ground in $t _ { 1 }$. If it is projected vertically downwards from the same point with the same speed, it reaches the ground in $t _ { 2 }$. Time required to reach the ground, if it is dropped from the top of the tower, is :\\
(1) $\sqrt { t _ { 1 } t _ { 2 } }$\\
(2) $\sqrt { t _ { 1 } + t _ { 2 } }$\\
(3) $\sqrt { t _ { 1 } - t _ { 2 } }$\\
(4) $\sqrt { \frac { t _ { 1 } } { t _ { 2 } } }$