An object is thrown vertically upward from the surface of a celestial body at a velocity of 12 meters per second. Its distance from the surface at t seconds is given by s(t) = -0.4t + 12t. (a) How fast is the object moving 3 seconds after being thrown? (b) How long after the object is thrown does it reach its maximum height? (c) How high will the object go? (a) The object's velocity after 3 seconds is m/sec (Round to the nearest tenth as needed.)