A body is thrown vertically upwards with an initial velocity u. It passes a point at a height h above the ground at time t1 while going up and at time t2 while falling down. Then the relation between u, t1 and t2 is
t1+t2=2ug
From the second equation of motion, h=ut−12gt2
⇒t2−2ugt+2hg=0
The roots of this quadratic equation are t1 and t2.
The sum of the roots is t1+t2=2ug. Hence, the correct option is (a).