2. A tuning fork is placed near the open end of the tube filled with water. The water level drops slowly, and the air is heard to resonate with the fork when the distance from the tube opening to the water level is 0.40m and again at 1.30m. (Given that the speed of air is 343m/s) (a) What is the air column's frequency? [6 marks] (b) If two tuning forks are vibrating with a distance apart, a man at the mid-point between the two forks experiences constructive interference. How far toward either wire must he walk to first experience destructive interference. [6 marks] (c) If the man runs from the left fork with a speed of 2m/s to the right fork, he hears different frequencies from the two forks. i . What is the frequency he hears from the left fork respectively? [4 marks] ii. What is the frequency he hears from the right fork respectively? [4 marks] (d) What beat frequency does the man hear? [6 marks]