When the effect of aerodynamic drag is included, the y-acceleration of a baseball moving vertically upward is u = -g kvg, while the acceleration when the ball is moving downward is ad = -g + kv2, where k is a positive constant and v is the speed in meters per second. If the ball is thrown upward with an initial speed of 30 m/s, determine the time t\" from ground to apex and the time td from apex to ground. Take k to be 0.004 m"1 and assume that g is constant