A horizontal constricted pipe known as a Venturi tube, can be used to measure the flow speed of an incompressible fluid. Determine the flow speed at point (smaller cross-section), if the pressure difference P1-P2 is known. (2 marks) (i) Submarine (sub A) travels through water at a speed of 8 m/s, emitting a sonar wave at a frequency of 1 4 Hz. The speed of sound in the water is 1 533 m/s. A second submarine (sub B) is located such that both submarines are traveling directly toward each other. The second submarine is moving at 9.00 m/s. (i) what frequency is detected by an observer riding on sub B as the subs approach each other