Science 4

4. a) Sound waves that have a very high frequency are called ultrasound or ultrasonic waves. Illustrate two (2) uses of ultrasound for each of the following sectors: i. medicine ii. industry [8 marks] b) A dolphin can tell in the dark that the ultrasound echoes received from two sharks come from two different objects only. If the sharks are separated by 3.50 m, one being that much farther away than the other. Criticize that the ability is not limited by its wavelength if the ultrasound has a frequency of 100 kHz. (Assume the temperature of water = 50*C) [8 marks] APU Level 0 Asia Pacific University of Technology & Innovation 20220623 EE003-4-0-ESC Final Exam Page 7 of 10 c) A metal rod heated from 30"C to 90"C. The final length of the rod is 120 cm. The coefficient of linear expansion is 3x10" /"C. Compute the initial length of the metal rod. [5 marks] d) A driver in a car is travelling on a road next to railway tracks. When the train approaches, it blows the horn which generates a sound with a single frequency of 420.0 Hz. The driver is driving at the speed of 18.0 m/s and the train's speed is 32.0 m/s. Further, the sound's speed is 340.0 m/s. Compute the frequency of the sound which the driver of the car will hear. [4 marks]