C | I | Question | Answer |
---|---|---|---|
14 | When two sound waves are out of phase by ____, destructive interference will occur. | 540° | |
14 | Which of the following ranges corresponds to the longest wavelengths? 1) infrasonic 2) audible 3) ultrasonic 4) all have the same wavelengths 5) both choices A and B are valid | infrasonic | |
14 | While standing at a crosswalk, you hear a frequency of 560 Hz from an approaching police car. After the police car passes, its frequency is 480 Hz. What is the speed of the police car? (speed of sound = 340 m/s) | 26.2 m/s | |
14 | You stand by the railroad tracks as a train passes by. You hear a 1 000-Hz frequency when the train approaches, which changes to 800 Hz as it goes away. How fast is the train moving? The speed of sound in air is 340 m/s. | 37.8 m/s |