A signal rocket explodes at a height of 200m above a ship on the surface of a smooth lake. The explosion sends out sound waves in all directions.Since the speed of sound in water (1500m/s) is larger than the speed of sound in air (340m/s), a sound wave can suffer total reflection at a water surface if it strikes at a sufficiently large angle of incidence. At what minimum distance from the ship will a sound wave from the explosion suffer total reflection?