A football player kicks a ball at ball at an angle of `30 ^(0)` with the horizontal with an initial speed of `20 m//s`. Assuming that the ball travels in a vertical plance, calculate (a) the time at which the ball reaches the highest point (b) maximum height reached (c ) the horizrontal range of the ball (d) the time for wich the ball is in air. `g =10 m//s^(2)`.