A projectile is thrown from ground at a speed `v_(0)` at an angle `alpha` to the horizontal. Consider point of projection as origin, horizontal direction as X axis and vertically upward as Y axis. Let t be the time when the velocity vector of the projectile becomes perpendicular to its position vector.
(a) Write a quadratic equation in t.
(b) What is the maximum angle a for which the distance of projectile from the point of projection always keeps on increasing? [Hint: Start from the equation you obtained in part (a)]

Answer

(a) `t^(2) - (3v_(0)sin alpha)/(g) t + (2v_(0)^(2))/(g^(2)) = 0` (b) `sin^(-1).(8)/(9)`