ABCABBC

()()

:

:

ACE BD ? A T

ff1T1Hz vTf

2 5 4 = 2 cm v= x / t =400/5=80 cm/sV=f f=40 Hz

0.1sT1/35T1/25 110 cm/s=4x= 1 n=4n+3 v= x / t =40n+30 T /v4/(40n+30)1/35 4/(40n+30)1/25n=2

1. 2. 3.

128 512

2000 324000

""

20>>

0331m/s10.6m/s

v3310.6t

m/sm/s343385014855170152038101450520011905100

? (A) (B) (C) B

330/3 (A)330 (B)110 (C)80 (D)64 (E)44 E

--

2020000audible sound 20000(ultrasound) 50,00070,000

SOund Navigation And Ranging

:

,,"".

,,,

,, .

(infrasound) 20

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