數中4 (2) - Ans.fyi 參考答案

數中4 (2)

2007-12-23 6:41 am

if the sound intensity from a radio is increased by 20%,what is the
increase in the corresonding sound intensity level?
(correct to 3sig.fig)

the strength of an earthquake was measured to be 7.9 on the
Richter scale .for hours later ,an aftershock bearing 1/20 of the strength of
the afterhock on the Richter scale.

ans.
1a by 0.0792 dB b by 0.792 dB c by 79.2 dB d 7.92 dB

2a 0.395 b 7.85 c 9.2 d 6.6

回答 (1)

2007-12-24 2:34 pm

✔ 最佳答案

1a
if the sound intensity from a radio is increased by 20%,what is the
increase in the corresonding sound intensity level?
(correct to 3sig.fig)
log10(1.2) Bel
=.0792 Bel
=.792 dB
The answer is b. 0.792dB

2a.
the strength of an earthquake was measured to be 7.9 on the
Richter scale .for hours later ,an aftershock bearing 1/20 of the strength of
the original quake. Calculate the strength of
the afterhock on the Richter scale.
7.9 + log10(1/20)
=7.9-1.30103
=6.6
The answer is d. 6.6

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