In the javelin throw at a track-and-field event, the javelin is launched at a speed of 30.0 m/s at an angle of 39.2 ° above the horizontal. As the javelin travels upward, its velocity points above the horizontal at an angle that decreases as time passes. How much time is required for the angle to be reduced from 39.2 ° at launch to 11.7 °?