Ch. 16 Review. (50 Points). Show Work for Credit Even in Multiple Choice Q

Ch. 16 Review. (50 points). Show work for credit even in multiple choice Q

1. A change in 40 dB sound intensity level will seem ______as loud (a) 40 times (b) 4 times (c) 1/4 times (d) 16 times

2. The sound intensity at a distance of 2 m from a 200W power stereo emitting spherical waves is approximately (a) 100 W / m2 (b) 4 W / m (c) 4 W / m2 (d) 100 W / m

3. The Andromeda galaxy is moving towards our Milky way galaxy on a collision course at a huge speed. To an observer on Earth, the spectrum of Andromeda galaxy should appear to be ______due to Doppler effect a) red shifted b) blue shifted c) unchanged in frequency

4. The speed of mechanical waves depends on a) frequency b) wavelength c) amplitude d) properties of the medium e) all of the above

5. If the frequency of the sound wave is doubled a. speed doubles b. wavelength doubles c. speed is same and wavelength is halved d. no change

6. Two boats are 14 m apart and are bobbing up and down. When one boat is at the crest the other is at the trough of the wave. There are no crests or troughs between the boats. If the boats take 3.5 sec for every cycle, then the velocity of the water wave is a) 8 m/sec b) 3.5 m/sec c) 2 m/sec d) 24.5 m/sec e) 4 m/sec 7. Two motors are running creating a noise level of 30 dB and 40 dB respectively. What is the total sound level heard? a) 70 dB c) 44 dB b) 10 dB d) 40.4 dB 8. A transverse wave of 5 Hz frequency and 3 m wavelength, travels along a 9 m string, under a tension of 25 N. The mass of the string is (a) 3 kg (b) 15 kg (c) 1 kg (d) 225 kg 9. The spectrum of far away galaxies appear to be ______due to Doppler effect (a) red shifted (b) blue shifted (c) unchanged in frequency

Free-Response

1. The 17000 Hz whine of a jet engine of an aircraft moving at 280 m/s is heard at what frequency by the pilot of a second aircraft, trying to overtake it at 300 m/s speed?

Identify given variables and unknown variable

Identify the equation to be used.

Box your answers with correct units. Show work