5. Combining two sounds of equal intensity will give a sound level ___________ t

Question

5. Combining two sounds of equal intensity will give a sound level ___________ than the sound level due to just one of them. (Points : 1)
twice as loud
3 dB higher
5 dB higher
10 dB higher
12 dB higher


6. You shout at a cliff, and hear your echo in 2 seconds. If the speed of sound in the air is 340 m/s, the distance of the cliff from you is __________.


(Points : 1)
340 m
170 m
680 m
450 m
800 m


7. A huge explosion is heard 20 miles away. How long does it take the sound to travel that far? (20 miles = 32,000 meters) (Points : 1)
44 s
61 s
74 s
93 s
cannot be determined


8. Water ripples are produced by making a cork oscillate up and down at a frequency of 5 Hz. The peaks of the ripples are 0.03 meters apart. What is the speed of the water ripples? (Points : 1)
0.55 m/s
0.15 m/s
1.15 m/s
5.0 m/s
cannot be determined


9. An electric current can consist of (Points : 1)
positive ions flowing in a liquid
negative ions flowing in a liquid
electrons flowing in a wire
all of the above
none of the above

Explanation / Answer

5. Let The intnsity of 1 i I

Then of two = 2I

Initial in dB = 10log(I/10-12) = 10*log(I) + 120

Final in dB = 10log(2I/10-12) = 10log(I) + 120 + 3.01

So answer is 3 dB higher

6. let the distance = x

2x = 340*2 => x = 340 m

7. speed of sound = 343.2 m/s

distance = 32000 m

t = distance/speed = 93.24 93 s

8. = 0.03 m

f = 5 Hz

Speed = *f = 0.15 m/s

9. All of the above

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