A train is approaching a signal tower at a speed of 40 ms

Question

1. What decibel reading corresponds to a pressure amplitude of 0.2 W/m²?

18 dB
20 dB
95 dB
72 dB
80 dB

2. A train passes a farm house at 60.0 m/s, and then the engineer sounds the 1200-Hz whistle.The air is still and the speed of sound is 340m/s What frequency will a person inside the farmhouse hear? Assume that the angle between the farmhouse and the train is negligible.

1020 Hz
988 Hz
1460 Hz
1410 Hz

3. A spaceship approaches a stationary light source at a speed 1.20 x 10⁷ m/s. The astronauts perceive the frequency of the light to be 4.39 Af- 1014 Hz. At what frequency is the source emitting light? (Note: The speed of light is 3.00 x 10⁸ m/s.)

4.05 Af- 1014 Hz
4.39 Af- 1014 Hz
4.76 Af- 1014 Hz
3.89 Af- 1014 Hz

4. Two cellos are being played in a duet. At a certain point, one cello plays a note of frequency 148.0 Hz and the other plays a note of frequency 148.5 Hz. What is the period of the beat?

0.25 s
2 s
0.5 s
448.25 s

5. What is the intensity level of a sound with an intensity of 6.5 x 10^-6 W/ m²?

11 dB
68 dB
34 dB
60 dB

6. In the diagram, the dot labeled S is moving from left to right. The dot represents a source of sound, and some of the wavefronts are shown.

You are standing to the right of S, meaning that the source of sound is approaching you. How do you perceive the sound in comparison to a person traveling with the source?

You hear the same pitch at the same volume.
You hear a higher pitch.
You hear the same pitch at louder volume.
You hear a lower pitch.

7. A train is approaching a signal tower at a speed of 40 m/s. The train engineer sounds the 1000-Hz whistle, while a switchman in the tower responds by sounding the 1200-Hz siren. The air is still and the speed of sound is 340m/s

What is the frequency of the train whistle tone that is heard by the switchman?

1000 Hz
340/380 Af- 1000 Hz
380/340 Af- 1000 Hz
300/340 Af- 1000 Hz
340/300 Af- 1000 Hz