Class 9 Practice Level 3 – Sound set – 1 Leave a Comment / By anushka kumari / July 11, 2024 Class 9 Practice Level 3 – Sound set – 1 Total questions: 15 1. If the sound intensity at a distance of 2 meters from a source is 80 dB, what will be the intensity at a distance of 8 meters from the source? 74 dB 68 dB 62 dB 56 dB None 2. A sound wave travels 1700 meters in 5 seconds in a certain medium. What is the speed of sound in that medium? 340 m/s 300 m/s 370 m/s 400 m/s None 3. A sound wave has a frequency of 500 Hz and a wavelength of 0.68 meters. What is the speed of sound in the medium? 300 m/s 340 m/s 360 m/s 400 m/s None 4. A train sounding its whistle at a frequency of 600 Hz approaches a stationary observer at a speed of 25 m/s. If the speed of sound is 340 m/s, what frequency does the observer hear? 615 Hz 645 Hz 675 Hz 705 Hz None 5. A pipe closed at one end has a length of 0.85 meters. If the speed of sound is 340 m/s, what is the fundamental frequency of the pipe? 50 Hz 100 Hz 150 Hz 200 Hz None 6. If the sound pressure level increases from 80 dB to 90 dB, by what factor does the sound pressure increase? 1.5 2 3 10 None 7. Two tuning forks of frequencies 256 Hz and 260 Hz are sounded together. What is the beat frequency? 2 Hz 4 Hz 6 Hz 8 Hz None 8. A sound wave is reflected off a wall and returns to the source in 2 seconds. If the speed of sound is 340 m/s, how far is the wall from the source? 170 meters 340 meters 510 meters 680 meters None 9. If two sounds have intensity levels of 70 dB and 80 dB respectively, what is the combined intensity level? 75 dB 62 dB 80 dB 90 dB None 10. A sound wave has an amplitude of 0.02 meters and a frequency of 200 Hz. What is the maximum speed of the particles of the medium through which the sound is traveling? (Assume the speed of sound in the medium is 340 m/s) 4 m/s 8 m/s 12 m/s 16 m/s None 11. A tuning fork resonates with an air column of length 0.75 meters. If the speed of sound is 340 m/s, what is the frequency of the tuning fork? 113 Hz 226 Hz 453 Hz 906 Hz None 12. Two sound waves of amplitudes 3 units and 4 units interfere constructively. What is the resulting amplitude? 1 unit 5 units 7 units 12 units None 13. An ambulance moving at 20 m/s emits a siren sound at a frequency of 800 Hz. What frequency does a stationary observer hear as the ambulance approaches? (Speed of sound = 340 m/s) 850 Hz 875 Hz 900 Hz 925 Hz None 14. A sonar device on a submarine sends out a signal and receives an echo 5 seconds later. If the speed of sound in water is 1500 m/s, what is the distance to the object? 3750 meters 4500 meters 6000 meters 7500 meters None 15. A vibrating string has a fundamental frequency of 220 Hz. What is the frequency of its second overtone? 220 Hz 440 Hz 660 Hz 880 Hz None 1 out of 15 Time's up