A scientist uses a variable frequency microphone/speaker system (sonar) to measure the depth of water. In freshwater (were sound travels at 1490 m/s) and 120 Hz sound is sent from a stationary ship to the bottom of a deep lake and the time interval between the generation and detection of the echo takes 1.14 seconds. What is the distance from the ship to the bottom of the lake?

Ahair dryer is basically a duct in which a few layers of electric resistors are placed. a small fan pulls the air in and forces it through the resistors where it is heated. air enters a 1200 w hair dryer at 100 kpa and 22°c and leaves at 47°c. the cross-sectional area of the hair dryer at the exit is 60 cm2. neglecting the power consumed by the fan and the heat losses through the walls of the hair dryer, determine (a) the volume flow rate of air at the inlet and (b) the velocity of the air at the exit.