For 1989 and 1990 Dave Johnson had the highest decathlon score in the world. When Johnson reached a speed of 32 ft/sec on the pole vault runway, his height above the ground t seconds after leaving the ground was given by h= -16t^2+32t. (The elasticity of the pole converts he horizontal speed into vertical speed.) Find the value of t for which his height was 12 ft. Determine how long Johnson was in the air. For how long was he more than 14ft in the air?