# Science

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1. Which one of the following frequencies of a wave in the air can be heard as an audible sound by the human ear?
A. 0.10 Hz
B. 10 Hz
C. 1,000 Hz (my Answer)
D. 100,000 Hz

2. If two waves with equal amplitudes and wavelengths travel through a medium in such a way that a particular particle of the medium is at the crest of one wave and at the trough of the other wave at the same time, what will happen to that particle?
A. The particle will vibrate with double amplitude due to resonance.
B. The particle will remain stationary due to interference.
C. The particle will move halfway to the crest due to reinforcement.
D. The particle will cause beats as a result of the wave combination. (my Answer)

3. Which of the following phenomena is taking place when sound waves are reflected from a surface along parallel lines?
A. Diffusion
B. Absorption (my Answer)
C. Refracting
D. Focusing

4. An overtone that's a whole number multiple of the fundamental frequency of a string is called a
B. pitch.
C. discordant sound.
D. scale.

5. Sound waves can't travel through
A. a solid.
B. a liquid.
C. an elastic material.
D. a vacuum. (my Answer)
6. The function of the eardrum in the middle ear is to
A. carry the sound energy to the brain.
B. collect the sound waves.
C. amplify the received sound.
D. vibrate with the frequency of the received sound. (my Answer)

7. A wave with a period of 0.008 second has a frequency of
A. 12.5 Hz.
B. 80 Hz.
C. 125 Hz.(my Answer)
D. 800 Hz.

8. During the process of steel production, the flaws in steel casting are detected by
A. infrasonic vibrations.
B. ultrasonic vibrations. (my answer)
C. longitudinal vibrations.
D. resonant vibrations.

9. When the temperature of the air is 25°C, the velocity of a sound wave traveling through the air is approximately
A. 320 m/s.
B. 332 m/s.
C. 347 m/s. (my Answer)
D. 357 m/s.

10. In a transverse wave that travels through a medium, the molecules of the medium vibrate
A. in the direction in which the wave travels.
B. at right angles to the direction in which the wave travels. (my Answer)
C. at twice the velocity of the molecules in a longitudinal wave.
D. with smaller amplitudes than the molecules in a longitudinal wave.

11. A wave front has the form of a
A. sine wave.
B. surface of a sphere. (my Answer)
C. straight line.
D. circle.

12. If a source of sound waves is rapidly approaching a person, the sound heard by the person appears to have
A. a frequency higher than the original frequency.
B. a period higher than the original period.
C. an amplitude lower than the original amplitude.
D. a pitch lower than the original pitch. (my Answer)

13. In a stringed musical instrument, the part that vibrates in resonance with the sound waves produced by the strings is called the
A. sounding board. (my Answer)
B. diatonic scale.
C. membrane.
D. reed.

14. If a wave hits a smooth surface at an angle of incidence of 40 degrees, the angle of reflection is
A. 0 degrees.
B. 40 degrees. (my Answer)
C. 80 degrees.
D. 90 degrees.

15. When a tuning fork vibrates over an open pipe and the air in the pipe starts to vibrate, the vibrations in the tube are caused by
A. harmonics.
B. reinforcement.
C. beats.
D. resonance. (my Answer)

16. When a sound from a source is refracted away from the surface of the earth, it gives an indication that the
A. air is cooler than the ground.
B. wind is blowing in the direction of the sound.
C. air has high humidity.
D. ground is cooling faster than the air. (my Answer)

17. A sound that's produced by a single wave at a constant frequency and with no overtones is called
A. a mellow sound.
B. a discordant sound.
C. a pure sound. (my Answer)
D. an average sound.

18. In which one of the following locations can a person hear the echo of a sound?
A. Less than 16.6 meters in front of the reflecting surface
B. At least 33.2 meters behind the reflecting surface
C. At least 16.6 meters in front of the reflecting surface (my Answer)
D. Less than 33.2 meters behind the reflecting surface

19. Rarefaction occurs only in a _______ wave.
A. longitudinal. (my Answer)
B. transverse.
C. sympathetic.
D. forced.

20. If a string vibrates at the fundamental frequency of 528 Hz and also produces an overtone with a frequency of 1,056 Hz, this overtone is the
A. first harmonic.
B. second harmonic. (my Answer)
C. third harmonic.
D. fourth harmonic.

21. A surface receiving sound is moved from its original position to a position three times farther away from the source of the sound. The intensity of the received sound thus becomes
A. three times as low.
B. nine times as low.
C. three times as high.
D. nine times as high. (my Answer)

22. The wavelength of a wave is the distance between
A. the amplitude and the normal position.
B. the crest and the following trough.
C. the rarefaction and the following compression. (my Answer)
D. two consecutive crests.

23. If a person is in front of a smooth surface from which a sound is reflected, the person would hear a sound that
A. has a higher intensity than the sound produced by the source.
B. seems to come from behind the surface.
C. has a higher pitch than the sound produced by the source.
D. seems to lack overtones. (my Answer)

24. In a stringed musical instrument, the sound frequency of a particular string can be increased by
A. lengthening the string.
B. loosening the string.
C. tightening the string. (my Answer)
D. increasing the string's thickness.

25. Through which one of the following mediums is the velocity of a sound wave the greatest?
A. Steel (my Answer)
C. Water
D. Air

• Science -

1. C Correct
2. D B PAGES 35-37
3. B D PAGE 28
4. A Correct
5. D Correct
6. D Correct
7. C Correct
8. B Correct
9. C Correct
10. B Correct
11. B Correct
12. D A PAGES 44,45
13. A Correct
14. B Correct
15. D Correct
16. D A PAGE 31
17. C Correct
18. C Correct
19. A Correct
20. B Correct
21. D B PAGES 20,21
22. C D PAGES 9,10
23. D B PAGES 25,26
24. C Correct
25. A Correct

• math -

ds

• Science -

thank u ur answers give a 88%

• Science -

1-c- 2b- 3 d -4a-5d-6d -7c-8b-9c-10b-11b-12a-13a-14b-15d-16a-17c18c-19a-20b-21b-22d-23b-24c-25a

• Science -

Number 19 is right ;)

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