1. A hammer strikes one end of a thick steel rail of length 8.50 m. A microphone located at the opposite end of the rail detects two pulses of sound, one that travels through the air and a longitudinal wave that travels through the rail. (a) Which pulse reaches the microphone first? (b) Find the separation in time between the arrivals of the two pulses.

1. Like most dolphins, "Sparky the Wonder Dolphin" uses echolocation (or sonar) by emitting high frequency "clicks" to locate objects in the water around her. Typical frequency of a dolphin's sonar click is 100 kHz, while the typical intensity of a sonar click at a distance of 1 m from a dolphin's head is 200 dB. The speed of sound in sea water is about 1520 m/s. If Sparky emits a sonar click that bounces off a school of tuna 20 km distant, a) how long must she wait to hear the reflected pulse, and b) what is the intensity in dB of the reflected pulse that she hears?

The sound level at a distance d=34 m from a loudspeaker is 70 dB. What is the power (in Watt) at which sound energy is being produced by the loudspeaker?. The threshold of hearing, lo = 1*10-12 W/m2, A. 0.5265 B. 0.3812 C. 0.1453 D. None E. 0.5812

11. An ultrasonic flow meter for measuring flow rate in a square channel uses two transducers that are placed at x = 0.5 m (Transducer 1) and x = 1.7 m (Transducer 2). x is measured along the length of the channel. The width of the channel is 0.2 m. The speed of sound through this medium is 1500 m/s and the flow rate is 0.4 m3/s Find the transit time (in us) of the wave from Transducer 1 to 2 and from Transducer 2 to 1 (in us)