2. A sound wave travels in water at speed 1480 m's for water at temperature 20 C. The speed of sound in air is given by the formula Vair = 331 + 0.67 , where 7 is the temperature in Celsius degrees, and the units of Vat are m/s. Two boats are at rest on a lake. Boat A sounds a horn as a signal to Boat B. At the same time as Boat A sounds its horn, a sound signal is sent from an underwater emitter submerged beside Boat A. The underwater sound signal is detected by a submerged receiver beside Boat B. (a) If the temperature of the air and the water is 20C, and the underwater wave is detected 4.00 s before the horn, what is the distance between the two boats? Give your answer to the nearest meter. (b) How many sound wavefronts would there be between the two boats if the frequency of the underwater wave is 400 Hz? Round to the nearest whole number of waves