The acceleration due to gravity near the surface of the earth is `vec(g)` . A ball is projected with velocity `vec(u)` from the ground.
(a) Express the time of flight of the ball.
(b) Write the expression of average velocity of the ball for its entire duration of flight. Express both answers in terms of `vec(u)` and `vec(g)`.

Answer

(a) `t = - (2vec(u).vec(g))/(|vec(g)|^(2))` (b) `vec(V_(av)) = vec(u) - (vec(g)(vecu.vec(g)))/(|vec(g)|^(2))`