Minta tolong teman............

Diket :
panjang tali, L = 4 m
cepat rambat gelombang, v = 6 m/s
periode, T = 4 sec
amplitudo, A = 15 cm

Tanya :
A. Amplitudo gelombang stasioner ujung bebas, As = __?
B. Simpangan gelombang saat t = 1/2 sec , Y = __?

Jawab :
step 1 
--------
Cari panjang gelombang,
λ = v.T
λ = 6. 4
λ = 24 meter

Step 2
---------
bilangan gelombang,
k = 2π/λ
k = 2π/24
k = π/12

 
A. Ujung Bebas,
amplitudo stasioner pada jarak x = L = 4 m adalah ... 
As = 2.A. cos k.x
As = 2. 15. cos (π/12). 4 
As = 2. 15. cos 60°
As = 15 cm

B. Simpangan saat t = 1/2 sec,
Y = As. Sin ω.t
Y = 15. Sin (2π/T).t
Y = 15. Sin (2π/4).(1/2)
Y = 15. Sin 45°
Y = 15. 1/2. √2
Y = 7,5.√2 cm


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