Gelombang Bunyi
• mendeskripsikan gejala dan ciri-ciri gelombang bunyi;
• menerapkan konsep dan prinsip gelombang bunyi dalam teknologi.
Setelah mempelajari bab ini, Anda harus mampu:
2A2D<29?52>6>32H2?8<2?5E?:2D2?A2252?H23E?H:E?:2 2<2?D6B2C2CE?H:D2?A2252?H23E?H:6B282>;6?:C3E?H:>6?;25:<2? 5E?:2:?:=63:9O9:5EAP?5252A2D>6?56?82B<2?>EC:<<2B6?2252?H2 A6B2>32D2?86=@>32?83E?H:H2?8C2>A2:<6D6=:?82?52+29E<29 ?52C:72DC:72D52?<=2C:7:<2C:86=@>32?83E?H:,=DB2C@?:<>6BEA2<2? C2=29C2DE;6?:C3E?H:H2?852A2D5:A2?42B<2?@=69<6=6=2G2B6=@>32?8 3E?H:D6BC63ED36BA6B2?C63282:OA6?8:?5B2P<6D:<2<6=6=2G2BD6B32?8 A252>2=2>92B:
*6=2:?E=DB2C@?:<D6B52A2D;6?:C86=@>32?83E?H:=2:??H2,?DE< >6?86D29E:=63:9=2?;EDD6?D2?8;6?:C;6?:C86=@>32?83E?H:C:72DC:72D 86=@>32?83E?H:52?76?@>6?276?@>6?2=2:??H2H2?836B<2:D2?56?82? 86=@>32?83E?H:C6BD2A6?6B2A2??H252=2>D6<?@=@8:A6=2;2B:=29>2D6B: A252323:?:C642B232:<
menerapkan konsep dan prinsip gejala gelombang dalam menyelesaikan masalah.
Hasil yang harus Anda capai:
A. Sifat Dasar
Gelombang Bunyi
B. Cepat Rambat Bunyi
C. Unsur Bunyi dan
Pemanfaatan
Gelombang Bunyi
D. Sifat-Sifat
Gelombang Bunyi
E. Dawai dan Pipa
Organa sebagai
Sumber Bunyi
F. Energi Gelombang
Bunyi
Kelelawar ladam kuda (horseshoe bat) dapat memancarkan gelombang bunyi ultrasonik yang berfungsi sebagai pengindra ketika terbang pada malam hari.
Bab
3
A. Sifat Dasar Gelombang Bunyi
A2<29?52>6?86D29E:AB@C6CD6B;25:?H23E?H:(25252C2B?H2 C6CE2DE H2?8 36B86D2B 252=29 CE>36B 3E?H: E?H: C66<@B ?H2>E< D6B56?82B <2B6?2 <6A2<2? 3E=E3E=E <65E2 C2H2A?H2 H2?8 >6>:=:<: 7B6<E6?C:C6<:D2B IE?H:C66<@B;2?8<B:<D6B56?82B2<:32D252?H2 86D2B2? <65E2 C2H2A?H2 H2?8 36B86C6<2? C642B2 D6BEC>6?6BEC 6=@>32?8:?7B2C@?:<5:A2?42B<2?@=69C66<@BA2EC56?82?7B6<E6?C: C2?82DB6?5295:32G29 ID6D2A:>2>AE5:D2?8<2A@=69A2ECH2?8 =2:?G2=2EAE?;2?8<2E2??H2B2DEC2?<:=@>6D6B
6B365256?82?CE>36BCE>36B3E?H:D6BC63ED3E?H:A2522=2D2=2D >EC:<H2?852A2D<:D256?82BD6B>2CE<86=@>32?82E5:@C@?:<E?H: H2?8<6=E2B52B:2=2D>EC:<36BC:72DD6B2DEBC69:?8825:?2>2<2?56?82? ?25252AE?3E?H:H2?8D:52<D6B2DEB5:?2>2<2?56C29
(6B92D:<2?#/$#3 (252 82>32B D6BC63ED D6B=:92D 86D2B2? =@?46?8>6?892C:=<2?86=@>32?83E?H:H2?8>6B2>32D>6=2=E:>65:2 E52B2>6?E;ED6=:?82H2?836BEA286=@>32?8=@?8:DE5:?2=
(25252C2B?H286=@>32?83E?H:52A2D>6B2>32D5:>65:E>2A2AE? (6B92D:<2? #$'. <6>2>AE2?>65:E>E?DE<>6?886D2B<2?A2BD:<6= 36B36523652329<2?252>65:E>H2?852A2D>6B652>3E?H:>:C2=?H22:B 6=@>32?83E?H:52A2D>6?E?;E<<2?C:72DC:72DE>E>86=@>32?8 C6A6BD:52A2D>6?82=2>::?D6B76B6?C:5:7B2<C:B67B2<C:52?B6C@?2?C: ?52;E822<2?>6>A6=2;2B:A6B:CD:G2CEA6BA@C:C:C6A6BD:CEA6BA@C:C:5E2 86=@>32?8 3E?H: H2?8 <64:= A6B36522? 7B6<E6?C:?H2 C69:?882 >6?8 92C:=<2?3E?H:<E2D=6>29C642B2A6B:@5:<H2?85:C63EDA6=2H2?82?3E?H: 6B52C2B<2?2B29B2>32D?H2D6B>2CE<86=@>32?82A2<293E?H::DE 82B?52>6>292>:?H2A6B92D:<2?#/$#3
#/$#3>6?E?;E<<2?CE>36B3E?H:36BEA286D2B2?>6>3B2? 32C 5BE> 6D2B2? C6=2AED H2?8 >6BEA2<2? 56?HED 36B5:>6?C: 5E2 5:A2?DE=<2?C642B236BE=2?8E=2?8@=6932D2CC6=2AEDC69:?882C6=2AED2<2? 36B86D2BC642B2A6B:@5:<#6D:<2C6=2AED36B86B2<<6=E2B2<2?D6B;25: A6>2>A2D2?E52B25:56A2??H2(6>2>A2D2? D6BC63ED>6?H6323<2? D6<2?2?E52B236BD2>329H2?85:C63ED526B29B2A2D2?)2A2D2?36B86B2< >6?;2E9:C6=2AED52=2>32D2C<646A2D2?3E?H:)2A2D2?52?B6?882?82? H2?8D6B36?DE<52B:A2BD:<6=A2BD:<6=E52B2>:B:A56?82?B2A2D2?52? B6?882?82?86=@>32?8=@?8:DE5:?2=A252C=:?<:"25:86=@>32?8=@?8:DE 5:?2=>6BEA2<2?C:72D52C2B86=@>32?83E?H:
#$'.
6A2D)2>32DE?H:636B2A2292? A252*E9EL
#/##*#0
'&+6/ '2#5#/$#5608+/4 :B
:B=2ED =E>:?:E> 6C:52?2;2 6=2C 6=:E> :5B@86? #2HE<6B2C ,52B2
Gambar 3.1 Gelombang bunyi dari lonceng yang bergetar merambat melalui media udara sampai ke telinga.
Gambar 3.2 Getaran dari membran bas drum membuat partikel udara merapat dan merenggang.
'$'.6//'/2'.#,#3+-104'2'.1/$#0)608+-'3,#-#0.#*41#.41#.$'3+-65&#.#/$6-6.#5+*#0
Tes Kompetensi Awal
6B52C2B<2? CE>36B?H2 3E?H: D6B>2CE< ;6?:C 86=@>32?82A2
A2<2986=@>32?83E?H:52A2D>6?82=2>:A@=2B:C2C: A2H2?85:>2<CE556?82?2E5:@C@?:<:?7B2C@?:<
52?E=DB2C@?:<
A2H2?85:>2<CE556?82?86>252?82E?8 A2<2986=@>32?8H2?85:A2?42B<2?A6>2?42BB25:@
D6B>2CE<86=@>32?8=@?8:DE5:?2=
rapatan
renggangan
x
tekanan udara
E?H:52A2DD6B56?82B;:<286D2B2?52B:CE>36B?H252A2D>6B2>32D 9:?882<6D6=:?82%65:2B2>32D2??H252A2D36BEA2I2DA252DI2D42:B 52?I2D82C"25:5:A6B=E<2?>65:E>E?DE<>6?;2=2B<2?3E?H:%2C:9 :?82D<29?52A6B:CD:G2D6?D2?83E?H:H2?852A2D>6B2>32D>6=2=E:C6ED2C 36?2?832C29H2?8<65E2E;E?8?H2D6B9E3E?8<2=6?8CECE56?82?32?DE2? CE2B2D6>2??52&29>6?EBED?5252A2D<293E?H:>6B2>32D5:52=2> F2<E>,?DE<>6?86D29E:;2G232??H2=2<E<2?=292<D:F:D2C36B:<ED
Aktivitas Fisika 3.1
Kata Kunci
• gelombang bunyi • gelombang longitudinal • gelombang infrasonik • gelombang audiosonik • nada• desah
• pelayangan bunyi • ruang vakum
Gelombang longitudinal adalah gelombang yang arah getarnya searah dengan arah rambatannya
Ingatlah
A2<29H2?85:>2<CE556?82?CE>36B3E?H: *63ED<2?C:72DC:72DH2?85:>:=:<:86=@>32?83E?H: A2<293E?H:52A2D>6B2>32D5:BE2?892>A2E52B2
%6?82A2
6B52C2B<2?2B2986D2B?H2D6B>2CE<86=@>32?8 2A2<293E?H::DE
A2<29A6B36522?2?D2B2?25252?56C29
Tes Kompetensi
Subbab
A
'3,#-#0.#*&#.#/$6-6.#5+*#0
B. Cepat Rambat Bunyi
6A2DB2>32D3E?H:D:52<36B82?DE?8A252D6<2?2?E52B2"25:;:<2 D6B;25:A6BE3292?D6<2?2?E52B246A2DB2>32D3E?H:D:52<36BE3296A2D B2>32D3E?H:36B82?DE?8A252CE9E*6>2<:?D:?88:CE9EE52B2C6>2<:? 36C2B46A2DA6B2>32D2?3E?H::526B29A68E?E?82?46A2DB2>32D3E?H: =63:9=2>32D52B:A25246A2DB2>32D3E?H:5:<2G2C2?A2?D2::E52B2 46A2DB2>32D3E?H:36B82?DE?8A252;6?:CA2BD:<6=H2?8>6>36?DE<E52B2 D6BC63ED(6BC2>22??H252A2D5:DE=:C<2?C63282:36B:<ED
$ N
A2H2?852A2D?52C:>AE=<2?52B:2<D:F:D2CD6BC63ED%6?82A2 <6D:<2E52B25:52=2>D23E?85::C2A=2>2<6=2>22?3E?H:;2>G6<6B D6BC63EDD:52<D6B56?82B 2=D6BC63ED>6>3E<D:<2?329G286=@>32?8 3E?H:>6>6B=E<2?>65:E>E?DE<>6B2>32D
Tugas Anda 3.1
Apakah bunyi termasuk gelombang elektromagnetik? Sebutkan alasan-alasan yang mendasari jawaban Anda tersebut.
Bunyi dalam Ruang Vakum Tujuan Percobaan
Menyelidiki apakah bunyi dapat merambat melalui ruang hampa.
Alat-Alat Percobaan
1. Jam weker
2. Tabung hampa udara (vakum)
Langkah-Langkah Percobaan
1. Bunyikan jam weker tanpa ditutup oleh tabung vakum.
2. Tutup jam weker dengan tabung vakum. Amati yang terdengar dari jam weker tersebut.
3. Gunakan sebuah pengisap untuk mengisap udara dalam tabung vakum secara perlahan-lahan.
2?5:?8<2?<646A2D2?3E?H:52=2>2=E>:?:E>52?2:B;:<2>@5E=EC.@E?8E?DE< 2=E>:?:E>Q& >>@5E=ECE=<2:BQ& >52?<646A2D2? 2:B<8 >
#7#$
:<6D29E:Q& > <8 > Q& > <8 >
$ $
& ><8 >
& > <8 >
> C > 4
#646A2D2?3E?H:5:2:BD6B?H2D2=63:9<64:=52B:A252<646A2D2?3E?H:52=2> 2=E>:?:E> 2=D6BC63ED5:C6323<2?42:B2?=63:9<@>AB6C:36==63:9>E529 36BE32936?DE<5:32?5:?8<2?56?82?I2DA252D>@5E=ECE=<42:B2?=63:9 <64:=5:32?5:?8<2?56?82?>@5E=EC.@E?8E?DE<I2DA252D
Contoh
3.1
Cepat rambat bunyi di udarabergantung pada suhu udara.
Ingatlah
Tugas Anda 3.2
Bandingkan nilai cepat rambat bunyi di udara yang Anda dapatkan dari percobaan dan dari buku referensi. Jika ada perbedaan, berikan analisis Anda mengenai hal tersebut.
Iskandar mendengarkan kembali suaranya sebagai gema dari sebuah tebing setelah waktu 4 detik. Jika
adalah perbandingan panas jenis
udara pada tekanan dan suhu konstan, serta Iskandar mengetahui bahwa suhu saat itu T kelvin dan massa molekul relatif udara M, Iskandar dapat menentukan jarak tebing menurut persamaan ....
a. MRT d. 6 MRT
b. 2 MRT e. 8 RT
M
c. 4 RT
M
UMPTN 1996 Pembahasan:
d = 2
vt v = RT
M
d =
2
RT t M =
4
2
RT M
Pembahasan Soal
6A2DB2>32D86=@>32?83E?H:5:E52B2A252CE9EL252=29> C":<2CE9E E52B2?2:<>6?;25:LD6?DE<2?46A2DB2>32D86=@>32?83E?H:D6BC63ED #7#$
#6D:<2CE9EE52B2?2:<<646A2D2?3E?H:2<2?C6>2<:?36BD2>329 2=D6BC63ED 5:C6323<2?86B2<2?86B2<2?>@=6<E=E52B2H2?8>6B2>32D<2?3E?H:36BD2>32946A2D
:<6D29E: #
#
$ > C
Contoh
3.2
#6D6B2?82?
<@?CD2?D2$2A=246
D6D2A2?E>E>82C" >@=#
CE9E>ED=2<82C<6=F:?
>2CC2>@=6<E=82C8B2> >@=
6A2DB2>32D3E?H:52=2>I2DA252D5:D6?DE<2?@=69>@5E=EC.@E?852? >2CC2;6?:CI2DD6BC63ED(6BC2>22??H252A2D5:DE=:C<2?C63282:36B:<ED
$ N
#6D6B2?82?
>@5E=EC.@E?8I2DA252D& > >2CC2;6?:CI2DA252D<8 >
:52=2>I2D42:B46A2DB2>32D3E?H:5:D6?DE<2?@=69>@5E=ECE=< 52? <6B2A2D2? >2CC2 ;6?:C 42:B2? D6BC63ED (6BC2>22??H2 52A2D 5:DE=:C<2?C63282:36B:<ED
$ N
#6D6B2?82?
>@5E=ECE=<& > >2CC2;6?:CI2D42:B<8 >
= 2 RT
M
Kata Kunci
• cepat rambat bunyi • konstanta Laplace • modulus Young • modulus Bulk
$
$
$
$ > C
"25:46A2DB2>32D3E?H:36BD2>329>6?;25:> C
Tes Kompetensi
Subbab
B
'3,#-#0.#*&#.#/$6-6.#5+*#0
+6?DE<2?<646A2D2?3E?H:52=2>82C<2B3@?5:@<C:52 A252CE9EL;:<236B2D>@=6<E='52?
6A2DB2>32D3E?H:A252CE9ELC2>256?82?> C +6?DE<2?46A2DB2>32D3E?H:A252CE9EL 6A2DB2>32D3E?H:52=2>82C'252=29> C
6B2A2<2946A2DB2>32D?H252=2>82C'
A252CE9EH2?8C2>2
:DE?846A2DB2>32D3E?H:A252C632D2?836C: Q& >52? 8B2> 4> 6B2A2<2=:=:A2D<29<646A2D2?3E?H:A25232;25:
32?5:?8<2?56?82?<646A2D2?3E?H:A2522=E>:?:E> ;:<2>@5E=EC.@E?8E?DE<32;252?2=E>:?:E>>2C:?8 >2C:?8Q& >52?Q& >C6BD2>2CC2 ;6?:C32;252?2=E>:?:E>>2C:?8>2C:?88B2> 4> 52?8B2> 4>
C. Unsur Bunyi dan Pemanfaatan Gelombang
Bunyi
,?CEBE?CEB3E?H:2?D2B2=2:?C63282:36B:<ED
1. Tinggi Nada Bunyi
(252A@<@<3292C2?C636=E>?H2?52D6=29>6?86D29E:329G23E?H: 5:D:>3E=<2?@=69CE2DE36?52H2?836B86D2B*6>2<:?32?H2<;E>=29 86D2B2?H2?85:92C:=<2?52=2>C2DEC6=2?8G2<DED6BD6?DE3E?H:H2?8 5:92C:=<2?2<2?C6>2<:??H2B:?8
(25282>32B#/$#3C6@B2?82?2<D6B=:92DC652?8>6?6>A6=<2? 32D2?8=:5:5:;2B:;2B:B@52C6A652H2?8C652?836BAED2B":<2B@52D6BC63ED 5:AED2BC6>2<:?46A2D2A2<293E?H:H2?85:92C:=<2?2<2?C6>2<:??H2B:?8 +6B?H2D2A252AED2B2?H2?8=2>32D3E?H:H2?8D6B56?82B36B?252 B6?529(252C22DAED2B2?B@52C6A6525:A6B46A2D3E?H:H2?8D6B56?82B 36B?252D:?88: 2=D6BC63ED>6>3E<D:<2?329G2D:?88:?25236B82?DE?8 A2527B6<E6?C:CE>36B3E?H:
2. Kuat Bunyi
#E2D 3E?H: H2?8 5:92C:=<2? 36B82?DE?8 A252 2>A=:DE5@ 86D2B2? (6B92D:<2?#/$#3H2?8>6?6B2?8<2?A6B4@322?A252C6?2B8:D2B (6D:<=29C2=29C2DEC6?2B8:D2B56?82?C:>A2?82?H2?8D:52<D6B=2=E 36C2B6?82B<2?32:<32:<<E2D3E?H:H2?85:92C:=<2?=2=E32?5:?8<2? 56?82?<E2D3E?H:H2?85:92C:=<2?@=69C6?2BH2?8C2>2?2>E?56?82? C:>A2?82? H2?8 =63:9 36C2B 52B:A252 C6>E=2 (6D:<2? >2?2<29 H2?8 >6?892C:=<2?3E?H:=63:9<E2D
3. Warna Bunyi
-2B?23E?H:>6BEA2<2?3E?H:<92CH2?85:D:>3E=<2?@=69CE2DE CE>36B3E?H:E?H:8:D2B36B365256?82?3E?H:3:@=2:DE<2B6?2252 G2B?23E?H:(6B36522?D6BC63EDD6B;25:<2B6?2823E?82??2522D2C52? ?25252C2B52B:CE>36B3E?H:36B36523652G2=2EAE?7B6<E6?C:?H2C2>2
Gambar 3.3
Lidi dipegang oleh seorang anak dan ditempelkan pada jeruji roda yang berputar.
Gambar 3.4
Percobaan kuat bunyi yang dihasilkan oleh getaran senar gitar dengan (a) simpangan yang kecil dan (b) simpangan yang besar.
2
4. Batas Pendengaran
?52D6?DED6=29>6?86D29E:329G2>2?EC:252?96G2?5:=6?8<2A: 56?82? 2=2D A6?56?82B2? H2?8 C6>AEB?2 &2>E? <6>2>AE2? A6?56?82B2??H236B365236522D2C<6>2>AE2?A6?56?82B2?5:E<EB 36B52C2B<2?7B6<E6?C:3E?H:
%2?EC:2?@B>2=>6>:=:<:32D2CA6?56?82B2?2?D2B296BDIC2>A2: 56?82?96BDI26B297B6<E6?C:D6BC63ED5:?2>2<2? #!# C652?8<2?526B297B6<E6?C:5:32G2996BDI5:C63ED ! 52?526B295:2D2C7B6<E6?C:56?82B2D2E5:2D2C96BDI5:C63ED
#" !
636B2A296G2?>2>AE>6?56?82B3E?H:E=DB2C@?:<329<2?96G2? C6A6BD: <6=6=2G2B H2?8 >6>:=:<: 2=2D A6?8=:92D2? D:52< C632:< 2=2D A6?56?82B2??H2 >6?88E?2<2? 3E?H: E=DB2C@?:< E?DE< >6?86D29E: 36?52H2?82525:56A2??H2
5. Pemanfaatan Gelombang Bunyi
6=@>32?83E?H:32?H2<5:>2?722D<2?52=2><69:5EA2?C692B:92B: >:C2=?H2E?DE<>6?6?DE<2?<652=2>2?=2ED>6?42B:CE>36B>:?H2<52? >6?56D6<C:<6BEC2<2?=@82>,?DE<>6?6?DE<2?<652=2>2?=2ED2=2D A6?56D6<C:H2?85:8E?2<2?5:C63ED! !#$" *@?2B 36<6B;256?82?>6>2?42B<2?86=@>32?8<6>E5:2?A2?DE=2?86=@>32?8 D6BC63ED 2<2? 5:D6B:>2 @=69 $ 6?82? >6?86D29E: <646A2D2? 86=@>32?8H2?85:E<EB52?G2<DED6>AE986=@>32?8D6BC63ED#652=2>2? =2ED52A2D5:D6?DE<2?56?82?>6?88E?2<2?A6BC2>22?36B:<ED
! $ "
N 2<D@BC6D6?8295:56A2?"A252'34#/##09>6?H2D2<2?C6D6?829 G2<DED6>AE952B:C@?2B<6D6>A2DA6>2?DE=2?
B6<E6?C:H2?85:8E?2<2?@=69C@?2B36B252A252526B29E=DB2C@?:< H2:DE5:2D2C96BDIB6<E6?C:D6BC63EDD:52<52A2D5:56?82B52? A2?;2?886=@>32?8A252526B29E=DB2C@?:<C2?82D<64:=C69:?8825:7B2<C: H2?8D6B;25:;E82C6>2<:?<64:=52?86=@>32?8D:52<2<2?>6?H632B #64:=?H2 A2?;2?8 86=@>32?8 H2?8 5:8E?2<2? 52A2D ;E82 5:8E?2<2? E?DE< >6?56D6<C: 36?5236?52 H2?8 <64:= (6?88E?22? 86=@>32?8 E=DB2C@?:<D6B52A2D;E82A2522=2D#" ! ,*=2DD6BC63ED E>E>?H25:8E?2<2?E?DE<>6?82?2=:C:C<692>:=2?2D2E>6?56D6<C: @B82?@B82?52=2>DE3E9
Gambar 3.6 Teknologi 3D USG terbaru sekarang dapat melihat organ-organ tubuh bayi dalam kandungan.
Sumber: www.mediajakartaselatan.com Gambar 3.5 Sonar dapat digunakan untuk mendeteksi kedalaman laut. pemancar penerima
gelombang ultrasonik
Contoh
3.3
*63E292=2DC@?2B5:8E?2<2?E?DE<>6?8E<EB<652=2>2?=2ED*6=2?8G2<DEH2?8 5:42D2D@=69C@?2BE?DE<86=@>32?8A6B2>32D2?C2>A2:<6>32=:=28:<6C@?2B252=29 C6<@?":<246A2DB2>32D86=@>32?85:52=2>2:B=2ED252=29> CD6?DE<2?=29 <652=2>2?=2EDD6BC63ED
#7#$
:<6D29E:$> C"C
!$ "> CQ QC>6D6B
"25:=2EDD6BC63ED>6>:=:<:<652=2>2?>6D6B
Kata Kunci
• tinggi nada• kuat bunyi
• audiosonik • infrasonik • ultrasonik
• resonansi • sonar
• ultrasonografi
1
2 3
4
Tes Kompetensi
Subbab
C
'3,#-#0.#*&#.#/$6-6.#5+*#0
?52>6?56?82B92=:=:?D2BC6<@?C6D6=29<:=2D D6B=:92D":<246A2DB2>32D3E?H:5:E52B2> C D6?DE<2?;2B2<2C2=<:=2DD6BC63ED52B:D6>A2D?52 *63E29 2=2D C@?2B 5:8E?2<2? E?DE< >6?8E<EB
<652=2>2?=2ED*6=2?8G2<DEH2?85:42D2D@=69C@?2B E?DE<86=@>32?8>6B2>32DC2>A2:<6>32=:<6C@?2B 252=29C6<@?":<2<652=2>2?=2ED>D6?DE<2? 46A2DB2>32D3E?H:5:52=2>2:B=2ED
%6?82A2<6=6=2G2BH2?8D6B32?8A252>2=2>92B:D:52< A6B?29>6?23B2<36?5236?52H2?82525:56<2D?H2
":<2D:?88:?2525:?2:<<2?3282:>2?2<29A6BE3292? H2?8D6B;25:A252
2 7B6<E6?C:
3 A2?;2?886=@>32?8 4 46A2DB2>32D86=@>32?8 5 2>A=:DE5@86=@>32?8
":<2<E2D3E?H:5:?2:<<2?3282:>2?2<29A6BE3292? H2?8D6B;25:A252
2 7B6<E6?C:
3 A2?;2?886=@>32?8 4 46A2DB2>32D86=@>32?8 5 2>A=:DE5@86=@>32?8
D. Sifat-Sifat Gelombang Bunyi
?52D6=29>6>A6=2;2B:C:72DC:72DE>E>D6?D2?886=@>32?8H2:DE A6>3:2C2? B67B2<C: A6>2?DE=2? B67=6<C: A6=6?DEB2? 5:7B2<C: :?D6B76B6?C:52?A@=2B:C2C:E?H:>6BEA2<2?C2=29C2DE36?DE<86=@>32?8 '=69<2B6?2:DE86=@>32?83E?H:;E82>6?82=2>:A6B:CD:G2A6B:CD:G2 D6BC63ED
1. Pemantulan Gelombang Bunyi
%6?82A2C22D?5236BD6B:2<5:C6<:D2BD63:?8C6=2=E2523E?H:H2?8 >6?:BE<2?CE2B2?52D6BC63ED%6?82A2CE2B2?52D6B56?82B=63:9 <6B2C <6D:<2 36B252 5: 52=2> 865E?8 #65E2 A6B:CD:G2 D6BC63ED >6?E?;E<<2?329G23E?H:52A2D5:A2?DE=<2?,?DE<>6>292>:D6?D2?8 A6>2?DE=2?3E?H:=2<E<2?=292<D:F:D2C36B:<ED
Tugas Anda 3.3
Gelombang bunyi merupakan gelombang longitudinal sehingga tidak dapat mengalami dispersi dan polarisasi. Diskusikanlah bersama teman Anda, mengapa hal tersebut bisa terjadi? Berikanlah penjelasan ilmiah mengenai hal tersebut.
Aktivitas Fisika 3.2
Pemantulan Bunyi Tujuan percobaan
Membuktikan peristiwa pemantulan bunyi.
Alat-Alat Percobaan
1. Weker 4. Dua buah pipa berdiameter 1 inci 2. Papan pemantul 5. Busur derajat
3. Meja 6. Kertas karton putih
Langkah-Langkah Percobaan
1. Susunlah alat seperti tampak pada gambar.
2. Letakkan jam weker di salah satu ujung pipa paralon.
3. Atur pipa paralon yang lain agar Anda dapat mendengar bunyi jam weker yang paling jelas.
2
3
Gambar 3.8 (a) Pada siang hari, arah rambat bunyi melengkung ke atas. (b) Pada malam hari, arah rambat bunyi melengkung ke bawah. Gambar 3.7 Proses pemantulan bunyi.
$E<:C2?82B:CH2?8?523E2DD6?D2?8CE5ED52D2?8CE5EDA2?DE= 52?82B:C?@B>2=A252A6>2?DE=2?3E?H:2<2?C2>256?82?#/$#3 (25282>32BD6BC63EDD6B=:92D329G2CE5ED52D2?8CE5EDA2?DE= 52?82B:C?@B>2=D6B=6D2<A252C2DE3:52?852D2B52?
%6?82A23E?H:52=2>BE2?82?D6BDEDEAD6B56?82B=63:9<6B2C$6D2< 5:?5:?8BE2?82?H2?8D6B=2=E56<2D>6?H6323<2?3E?H:A2?DE=D:52<4E<EA G2<DEE?DE<>6B2>32DC69:?8823E?H:52D2?852?3E?H:A2?DE=D6B56?82B C642B236BC2>22? 2=D6BC63ED>6>3E<D:<2?329G23E?H:A2?DE=52A2D >6>A6B<E2D3E?H:2C=:?H2!DE=29C6323?H2CE2B2>EC:<2<2?D6B56?82B=63:9 <6B2C5:52=2>BE2?82?52B:A2525:=2A2?82?D6B3E<26B365256?82?86>2 H2?8D6B;25:;:<2?5236BD6B:2<5:526B2936BD63:?8"2B2<D63:?852? CE>36B3E?H:H2?84E<EA;2E9>6?H6323<2?3E?H:A2?DE=>6>6B=E<2? G2<DEH2?84E<EA=2>2E?DE<>6B2>32DC2>A2:A6?56?82B2?<:32D?H2 3E?H:A2?DE=2<2?D6B56?82BC6D6=293E?H:2C=:636B2A2A6B:CD:G2D6BC63ED >6BEA2<2?A6?82=2>2?H2?8C6B:?8?52D6>E<2?
2.
Pembiasan Gelombang Bunyi
?52 D6=29 >6?86D29E: 86=@>32?8 3E?H: >6B2>32D<6C6>E22B2952?86=@>32?83E?H:D:52< 52A2DD6BA@=2B:C2C:%6?82A2A252>2=2>92B:CE2B2 25I2?2D2ECE2B2D6B:2<2?H2?84E<EA;2E9D6B56?82B =63:9;6=2C52B:A252C:2?892B:(252C:2?892B:CE9E E52B25:A6B>E<22?=63:9D:?88:52B:A2525:2D2C?H2 2=D6BC63ED>6?H6323<2?=2A:C2?E52B2A252328:2? 2D2C=63:9B2A2D52B:A2525:32G29?H2*632=:<?H2A252 >2=2>92B:=2A:C2?E52B25:A6B>E<22?=63:9B2A2D 52B:A2525:2D2C?H2<:32D?H2A252C:2?892B:;:<2 CE>36B 3E?H: 52D2?8 C642B2 9@B:I@?D2= D6B9252A A6?56?82B52A2D5:A2CD:<2?2B29B2>32D3E?H:2<2?>6=6?8<E?8<62D2C C652?8<2?A252>2=2>92B:2B29B2>32D3E?H:2<2?>6=6?8<E?8<6 32G29(6B92D:<2?#/$#3
A2H2?82<2? D6B;25:;:<23E?H:52D2?8?H2>6B2>32DF6BD:<2=<6 32G29(252>2=2>92B:2B29B2>32D3E?H:5:3:2C<2?>6?56<2D:82B:C ?@B>2=*632=:<?H2A252C:2?892B:2B29B2>32D3E?H:5:3:2C<2?>6?;2E9: 82B:C?@B>2=
*6CE2: 56?82? 9E<E> A6>3:2C2? 86=@>32?8 329G2 86=@>32?8 52D2?852B:>65:E><EB2?8B2A2D<6>65:E>=63:9B2A2D2<2?5:3:2C<2? >6?56<2D:82B:C?@B>2=2D2EC632=:<?H2
3. Difraksi Gelombang Bunyi
A2<2986=@>32?83E?H:52A2D>6?82=2>:5:7B2<C:2D2EA6=6?DEB2? (6B:CD:G2A6=6?DEB2?3E?H:52A2D5:2>2D:<6D:<2?52>6?56?82B56BE 3E?H:>@3:=>6=:?D2C:526B29A6B3E<:D2?H2?836B<6=@<CE2B2A6B42<2A2? D6>2?D6>2??525:BE2?82?H2?836B36522D2E<242A6>32D2C=@<6D A6>32H2B2?5:C63E2932?<H2?8C6?82;25:3E2D56?82?3636B2A2=E32?8 <64:=282B86=@>32?83E?H:D:52<>6>2?DE=G2=2EAE?2B29B2>32D3E?H: D:52< 36BEA2 82B:C =EBEC +:82 A6B:CD:G2 D6BC63ED >6BEA2<2? 4@?D@9 A6?6B2A2?5:7B2<C:3E?H:"25:2A2<29H2?85:>2<CE556?82?5:7B2<C: :DE :7B2<C: 252=29 A6B:CD:G2 A6=6?DEB2? 86=@>32?8 <6D:<2 >6=6G2D: 46=29H2?8E<EB2?46=29?H2C6@B5656?82?A2?;2?886=@>32?8?H2
A N C
r i
Pelayangan bunyi terjadi karena adanya interferensi dua gelombang yang frekuensinya berbeda sedikit.
$2=E >6?82A2 86=@>32?8 3E?H: >E529 >6?82=2>: 5:7B2<C: 6=@>32?83E?H:5:E52B2>6>:=:<:A2?;2?886=@>32?8C6<:D2B3636B2A2 C6?D:>6D6B C2>A2: 3636B2A2 >6D6B 2?5:?8<2? 56?82? 4292H2 H2?8 >6>:=:<:A2?;2?886=@>32?836B<:C2B>>!DE=29C6323?H286=@>32?8 3E?H:=63:9>E529E?DE<D6B5:7B2<C:
4. Interferensi Gelombang Bunyi
#6D:<2?5236B5:B:5:56A2?5E2#! A6?86B2CCE2B2C63282: CE>36B3E?H:<6>E5:2?36B;2=2?=EBECC6;2;2B56?82?82B:CA6?89E3E?8<65E2
#! D6BC63ED+2<=2>2C6D6=29:DE?522<2?>6?56?82B3E?H:=6>29 52?C6C22D<6>E5:2?D6B56?82B3E?H:<E2DE?H:<E2DD6B;25:<6D:<2CEA6BA@C:C: 52B:5E286=@>32?83E?H:>6?892C:=<2?:?D6B76B6?C:56CDBE<D:7!?D6B76B6?C: D6BC63EDD6B;25:;:<23652=:?D2C2??H2>6BEA2<2?<6=:A2D2?3:=2?82?3E=2D52B: C6D6?829A2?;2?886=@>32?83E?H:C642B2>2D6>2D:C5:DE=:C<2?C63282:36B:<ED
!
56?82?
52?36BDEBEDDEBEDE?DE<3E?H:<E2DA6BD2>23E?H: <E2D<65E252?3E?H:<E2D<6D:82
5. Pelayangan Bunyi
!?D6B76B6?C: H2?8 5:D:>3E=<2? 52B: 5E2 86=@>32?8 3E?H: 52A2D >6?H6323<2?A6B:CD:G2A6=2H2?82?3E?H:H2:DEA6?8E2D2?52?A6=6>292? 3E?H: 2=D6BC63EDD6B;25:2<:32DCEA6BA@C:C:5E286=@>32?8H2?8>6>:=:<: 7B6<E6?C:H2?8C65:<:D36B365252?>6B2>32D52=2>2B29H2?8C2>2 "25:C2DEA6=2H2?82?5:567:?:C:<2?C63282:5E23E?H:<6B2C2D2E5E2 3E?H:=6>29H2?8D6B;25:C642B236BEBED2?=2H2?82?<E2DN=6>29N <E2D2D2E=6>29N<E2DN=6>29
":<2<65E286=@>32?83E?H:D6BC63ED>6B2>32D36BC2>22?2<2? >6?892C:=<2?3E?H:A2=:?8<E2DC22D72C6<65E2?H2C2>2":<2<65E2 86D2B2?36B=2G2?2?72C62<2?5:92C:=<2?3E?H:A2=:?8=6>29
%:C2=<2? 5E2 CE>36B 3E?H: >6>:=:<: 7B6<E6?C: 52? C65:<:D 36B3652C:>A2?82?C6D:2A86=@>32?8A252A@C:C:D6BD6?DE252=29
&C:? "52?&C:? "
6?82?56>:<:2?CEA6BA@C:C:C:>A2?82?<65E286=@>32?8D6BC63ED252=29
C:? C:?
& & & " " &
C:? " C:? "56?82?>6?88E?2<2?2DEB2?C:?EC2<2?5:A6B@=69
4@C C:?
& " " " "
4@C C:?
" "
":<2 52? >2<2
f 52?
(6BC2>22?CEA6BA@C:C:52A2D5:DE=:C<2?>6?;25:
&4@C "
C:? "AC:? " N
Kata Kunci
• dispersi• refraksi • refleksi • difraksi • interferensi • polarisasi • superposisi
sin A + sin B = 2 cos 21 (A–B) sin 12 (A+B)
E. Dawai dan Pipa Organa sebagai Sumber Bunyi
1. Frekuensi Gelombang pada Dawai
?52D6=29>6>A6=2;2B:329G236?5236?52H2?836B86D2B>6BEA2<2? CE>36B3E?H:D6D2A:D:52<C6>E23E?H:52A2D5:56?82B@=69D6=:?82>2?EC:2 2= D6BC63ED 5:C6323<2? D6=:?82 >2?EC:2 ?@B>2= >6>:=:<: 7B6<E6?C: 2>32?8>:?:>2=H2:DE7B6<E6?C:D6B6?52952B:CE>36B3E?H:H2?8>2C:9 52A2D5:D6B:>2@=69D6=:?82
Tes Kompetensi
Subbab
D
'3,#-#0.#*&#.#/$6-6.#5+*#0
"6=2C<2?A6?86BD:2?5:7B2<C:86=@>32?83E?H: ":<2252D:82CE>36B3E?H:H2?8:56?D:<5:=6D2<<2?
>2C:?8>2C:?836B;2B2<>56?82?H2?8=2:??H2 <2A2?<29D6B;25::?D6B76B6?C:>2<C:>E>52B:<6D:82 CE>36B3E?H:D6BC63ED
E23E29C6?2BH2?8:56?D:<>6>36B:<2??25252C2B 56?82?7B6<E6?C: I":<2D682?82?C2=29C2DE 52G2:5:D2>32936B2A27B6<E6?C:A6=2H2?82?H2?8 D6B;25:
E2ED2CC6?2BH2?8:56?D:<>6>36B:<2??25252C2B56?82?7B6<E6?C: I":<2 D682?82?C2=29C2DEC6?2B5:D2>32936B2A2A6=2H2?82?H2?8D6B;25:
#7#$
:<6D29E: I
52A2D5:9:DE?856?82?A6BC2>22?
Hz
I
B6<E6?C:A6=2H2?82?5:A6B@=6956?82?>6?88E?2<2?'34#/##09252=29
NN IN I
"25:7B6<E6?C:A6=2H2?82??H2252=29N I
Contoh
3.4
4@C
"
N
6B52C2B<2?'34#/##09:?D6?C:D2C3E?H:2<2?>2<C:>2=;:<2
&'=69<2B6?2:DE=2H2?82?3E?H:D6B;25:;:<2 4@C
"
36B?:=2:52?NC69:?8827B6<E6?C:=2H2?82??H2252=29
fp(f1 f2) N
#6D6B2?82?
7B6<E6?C:A6=2H2?82? I
7B6<E6?C:86=@>32?8& I
7B6<E6?C:86=@>32?8& I
Dua buah dawai baja yang identik memberikan nada dasar dengan frekuensi 400 Hz. Bila tegangan dalam salah satu dawai ditambah 2%, frekuensi pelayangan yang terjadi adalah ....
a. 0 Hz d. 6 Hz b. 2 Hz e. 8 Hz c. 4 Hz
Tes ITB 1975 Pembahasan:
Diketahui:
f0 = 400 Hz
Tegangan ditambah 2%
p’ = F + 2% F = 1,02 F
maka
0 ’ 1,02 1,01
f F F f F F
sehingga frekuensi layangannya adalah
fp = (f2 – f1) = (1,01 f0 – f0) = 0,01 f0
= 0,01 · 400 Hz = 4 Hz
Gambar 3.9 (a) Nada dasar f0; (b) Nada atas pertama f1; (c) Nada atas kedua f2; (d) Nada atas ketiga f3.
(@=286D2B2?52G2:A252#/$#3#>6?892C:=<2??25252C2B 56?82?2D2E >2<2
$ $
(@=286D2B2?52G2:A252#/$#3 $>6?892C:=<2??2522D2C A6BD2>256?82?2D2E>2<2
$ $
(@=286D2B2?52G2:A252#/$#3%>6?892C:=<2??2522D2C<65E2 56?82?2D2E>2<2
$ $ $
(@=286D2B2?52G2:A252#/$#3&>6?892C:=<2??2522D2C<6D:82 56?82?2D2E>2<2
$ $ $
(6B32?5:?82? 7B6<E6?C: ?252?252 A252 52G2: H2?8 5:92C:=<2? 36BEA2A@=286=@>32?8C6A6BD:A252#/$#3252=29C63282:36B:<ED
N
'=69<2B6?246A2DB2>32D86=@>32?8A25252G2:C6CE2:56?82?92C:=
2'3%1$##0'.&'H2:DE$ >2<25:A6B@=69 2 7B6<E6?C:?25252C2B
3 7B6<E6?C:?2522D2CA6BD2>2
4 7B6<E6?C:?2522D2C<65E2
5 7B6<E6?C:?2522D2C<6
N
2 3 4 5
0
1
2
1 2 22
3 2
*2=29C2DECE>36B3E?H:252=2952G2:8:D2B&252H2?85:92C:=<2? 52G2:8:D2B52A2D5:E329E32956?82?42B2>6?6<2?C6?2BA252D:D:< D:D:< D6BD6?DE (@=2 86=@>32?8 H2?8 52A2D D6B;25: A252 52G2: 8:D2B 5:DE?;E<<2?A252#/$#356?82?36BE329E329
*2DE52G2:52A2D>6>36?DE<36B3282:7B6<E6?C:2D2EA@=286D2B2? C6A6BD:D2>A2<A252#/$#3
Echolocation adalah bentuk sensor yang digunakan oleh binatang seperti kelelawar, paus, dan lumba-lumba. Binatang tersebut memancarkan gelombang suara (gelombang longitudinal), kemudian dipantulkan oleh objek. Gelombang pantul kemudian dideteksi oleh binatang tersebut. Gelombang echolocation yang dipancarkan oleh kelelawar memiliki frekuensi sekitar 175.000 Hz.
Echolocation is a form of sensory perception used by animals such as bats, toothed whales, and porpoises. The animal emits a pulse of sound (a longitudinal wave) which is reflected from objects. The reflected pulse is detected by the animal. Echolocation wave emitted by bats have
frequencies of about 175.000 Hz.
Informasi
untuk Anda
2. Pipa Organa dan Pola Gelombangnya
+6=29?52<6D29E:329G236?52H2?836B86D2B52A2D>6?892C:=<2? 3E?H:+:52<92?H236?52A252DC6A6BD:52G2:D2=:>2EAE?A6=2D=@82> H2?852A2D36B86D2B86D2B2?AE?52A2DD6B;25:A25282C>:C2=?H2E52B2 6D2B2?<@=@>E52B2A252C6BE=:?82<2?>6?892C:=<2?3E?H:+:?88: ?252H2?85:A6B@=6952B:C63E29C6BE=:?852A2D5:2DEB7B6<E6?C:?H2: 2?D2B2 A6B2?8<2D >EC:< C656B92?2 H2?8 52A2D >6?892C:=<2? 86D2B2? <@=@>E52B2C6=2:?C6BE=:?8252=29A:A2@B82?2+6B52A2D5E2>242> A:A2@B82?2H2:DEA:A2@B82?2D6B3E<252?A:A2@B82?2D6BDEDEA
a. Pipa Organa Terbuka
(:A2@B82?2D6B3E<2252=292=2DD:EA36BEA2D23E?8H2?8<65E2E;E?8 A6?2>A2?8?H2D6B3E<2#65E2E;E?8A:A2@B82?2D6B3E<2>6?;25:A6BED 86=@>32?8A252<@=@>E52B2(@=286=@>32?8H2?85:92C:=<2?C6A6BD: D2>A2<A252#/$#3 B6<E6?C:H2?85:92C:=<2?@=69A:A2@B82?2 D6B3E<2252=29C63282:36B:<ED
&25252C2B2D2E
B6<E6?C:H2?85:92C:=<2?
$ $
Gambar 3.10 Seruling merupakan pipa organa terbuka.
*6ED2C52G2:H2?8<65E2E;E?8?H2D6B:<2D>6>:=:<:A2?;2?8>>2CC2;6?:C?H2 8 4>>6?892C:=<2?7B6<E6?C:?25252C2B
I 2 :DE?8=2982H2D682?82?52G2:
3 6B2A2<2936C2B7B6<E6?C:52?A2?;2?886=@>32?8A252?2522D2CA6BD2>2 4 +6?DE<2?=297B6<E6?C:52?A2?;2?886=@>32?8A25252G2:E?DE<?2522D2C
<65E2 #7#$
:<6D29E:> <8 4>
I
2 6?82?>6?88E?2<2?'34#/##09E?DE<?25252C2B5:A6B@=69
2D2E
QN<8 4> I
&
"25:36C2B82H2D682?82?52G2:252=29& 3 B6<E6?C:?2522D2CA6BD2>2252=29
2D2E I I
(2?;2?886=@>32?8A252?2522D2CA6BD2>2252=29>
4 B6<E6?C:A252?2522D2C<65E2252=29
2D2E I I (2?;2?886=@>32?8A252?2522D2C<65E2252=29
2D2E >
Contoh
3.5
(6BC2>22?7B6<E6?C:?252?252D6BC63ED<2=:A6BD2>25:E?8<2A<2?@=69
Gambar 3.11
Pola gelombang resonansi suatu pipa organa terbuka.
nada dasar atau harmonik pertama
nada atas pertama atau harmonik kedua
nada atas ketiga atau harmonik ketiga
0
1 2
1
3
2
&2522D2CA6BD2>22D2E
B6<E6?C:H2?85:92C:=<2?
$ $
&2522D2C<65E22D2E
B6<E6?C:H2?85:92C:=<2? $$
&2522D2C<6?
B6<E6?C:H2?85:92C:=<2?
$
N
(6B32?5:?82?7B6<E6?C:86=@>32?8H2?85:>:=:<:<@=@>E52B2A252 A:A2@B82?2D6B3E<2C2>256?82?A6B32?5:?82?7B6<E6?C:86=@>32?8 A25252G2:(6B32?5:?82?7B6<E6?C:H2?85:92C:=<2?@=69C6D:2AA@=2 86=@>32?8E?DE<A:A2@B82?2D6B3E<2252=29
$ $ $
N
'34#/##09 H2?8>6BEA2<2?A6B32?5:?82?7B6<E6?C:5:<6?2= C63282:6-6/ '3016..+52?>6BEA2<2?A6B32?5:?82?3:=2?82? 3:=2?82?3E=2D
*63E29A:A2@B82?2D6B3E<2A2?;2?8?H24>+6?DE<2? ?25252C2BH2?85:92C:=<2?A:A2D6BC63ED;:<246A2DB2>32D 3E?H:5:E52B2> C
#7#$
:<6D29E:A2?;2?8A:A2 4>>
46A2DB2>32D3E?H:$> C
6?82?>6?88E?2<2?'34#/##097B6<E6?C:?25252C2B5:A6B@=69
2D2E>2<2 > >
Contoh
3.6
1 40cm
2
*H2B2DD6B;25:?H2?25252C2BH2:DE > C I >
$
*63E29A:A2@B82?2D6B3E<2H2?8A2?;2?8?H2>52?7B6<E6?C:92B>@?:<?H2 36BDEBEDDEBED I52? I+6?DE<2?46A2DB2>32D3E?H:A252A:A2@B82?2 D6BC63ED
b. Pipa Organa Tertutup
(:A2@B82?2D6BDEDEA252=292=2DD:EA36BEA2D23E?8H2?8C2=29C2DE E;E?8A6?2>A2?8?H2D6BDEDEA*2=29C2DEE;E?8A:A2@B82?2D6BDEDEA >6?;25:C:>AE=86=@>32?8A252<@=@>E52B252?E;E?8=2:??H2H2?8 D6B3E<2>6?;25:A6BED86=@>32?8(@=286=@>32?8H2?85:92C:=<2?D2>A2< C6A6BD:#/$#3 B6<E6?C:H2?85:92C:=<2?@=69A:A2@B82?2D6BDEDEA 252=29C63282:36B:<ED
&25252C2B2D2E
7B6<E6?C:H2?85:92C:=<2?
$ $
&2522D2CA6BD2>22D2E
7B6<E6?C:H2?85:92C:=<2?
$ $
&2522D2C<65E2
2D2E
7B6<E6?C:H2?85:92C:=<2?
$ $
&2522D2C<6N? 2D2E
B6<E6?C:H2?85:92C:=<2?
$
N
(6B32?5:?82?7B6<E6?C:H2?85:92C:=<2?@=69C6D:2AA@=286=@>32?8 E?DE<A:A2@B82?2D6BDEDEA252=29
$ $ $
N
'34#/##09 H2?8>6BEA2<2?A6B32?5:?82?7B6<E6?C:5:<6?2= C63282:6-6/ '3016..+52?>6BEA2<2?A6B32?5:?82?3:=2?82? 3:=2?82?82?;:=
Gambar 3.12 Pola gelombang resonansi pada suatu pipa organa tertutup. harmonik kedua
1
3 4
harmonik ketiga
2
5 4
harmonik pertama
0
1 4
#7#$
%:C2=<2?? I52?? I
6?82?>6?88E?2<2?'34#/##095:A6B@=69 ?N?JNK $
I
$
I $
*63E29A:A2@B82?2D6BDEDEA>6>:=:<:A2?;2?84>A23:=246A2DB2>32D3E?H: C22D:DE> CD6?DE<2?7B6<E6?C:?25252C2B?2522D2CA6BD2>252??2522D2C <65E2
#7#$
:<6D29E:4>>$> C
6B52C2B<2?'34#/##09 $5:A6B@=69
M ?25252C2B
$ >> C I
M ?2522D2CA6BD2>2
01 I
M ?2522D2C<65E201 I
Contoh
3.8
*63E29A:A2@B82?2D6B3E<256?82?A2?;2?84>D6B;25:3E29C:>AE=&252 A:A2@B82?2D6BC63ED36B6C@?2?C:56?82?A:A2@B82?2D6BDEDEA52?>6>36?DE< 3E29C:>AE=6B2A2A2?;2?8A:A2@B82?2H2?8D6BDEDEA
#7#$
)6C@?2?C:D6B;25:;:<2C2>256?82?
(2?;2?8A:A2@B82?2D6B3E<24>D6B;25:C:>AE=52?A6BED
C69:?882 2D2E >2<2 4> 4> (252A:A2@B82?2D6BDEDEAD6B;25:C:>AE=52?A6BED C69:?882 2D2E >2<2 $
56?82?>6?88E?2<2?CH2B2DB6C@?2?C:A2?;2?8A:A2@B82?2D6BDEDEA52A2D5:9:DE?8
4> 4> $ $
Contoh
3.9
Pipa organa terbuka A dan pipa organa tertutup sebelah B memiliki panjang yang sama. Perbandingan frekuensi nada atas pertama antara pipa organa A dengan pipa organa B adalah ....
a. 1 : 1 d. 3 : 2 b. 2 : 1 e. 4 : 3 c. 2 : 3
UMPTN 1995 Pembahasan:
Pipa organa terbuka: 3 1 , , , ....
2 2
A
Pada nada atas pertama:
A A A v v f x
Pipa organa tertutup: 3 5 1 , , , .... 4 4 4
B
Pada nada atas pertama:
3 4
4 3
B B
3 4 4 3 B B B
v v v
f
Untuk AB, diperoleh 4 3 3 4 A A B B v f
f v
Jawaban: e
Pembahasan Soal
3. Resonansi
(6B:CD:G2:<ED36B86D2B?H2CE2DE36?52<2B6?225236?52=2:?H2?8 36B86D2B5:C63ED !!*H2B2DD6B;25:?H2B6C@?2?C:252=297B6<E6?C:86D2B <65E236?5292BECC2>22D2E7B6<E6?C:36?52H2?8:<ED36B86D2BC2>2 56?82?<6=:A2D2? 3:=2?82? 3E=2D 52B: 7B6<E6?C: 36?52 H2?8 36B86D2B (6B92D:<2?5E24@?D@9A6B:CD:G2B6C@?2?C:36B:<ED:?:
a. Resonansi pada Garputala
":<2C63E2982BAED2=25:AE<E=82BAED2=2D6BC63ED36B86D2BC6A6BD: A252#/$#3 B6<E6?C: 86=@>32?8 3E?H: H2?8 5:92C:=<2? 36B82?DE?8A25236?DE<36C2B52?3292?=@82>82BAED2=2D6BC63ED #6D:<25:56<2D<2?A25282BAED2=2H2?8=2:?52?>6>:=:<:7B6<E6?C:3E?H: C2>2 82BAED2=2<65E22<2?:<ED36B86D2B(6B:CD:G2:<ED36B86D2B?H2 82BAED2=2H2?8<65E25:C63EDB6C@?2?C:
Gambar 3.13
Aktivitas Fisika 3.3
gelas air mineral
paralon garputala
selang plastik
gabus neon
Cepat Rambat Bunyi Tujuan Percobaan
Mengukur cepat rambat bunyi di udara.
Alat-Alat Percobaan
1. Garputala
2. Lampu neon yang sudah tidak terpakai 3. Botol air mineral 100 m
4. Selang plastik berdiameter 1,5 cm dan panjang 2 m 5. Pipa paralon berdiameter 3 cm dan panjang 1 m 6. Penjepit
7. Penggaris
8. Gabus sebagai sumbat
Langkah-Langkah Percobaan
1. Rangkailah alat-alat tersebut seperti pada gambar. 2. Isilah lampu neon dengan air sampai ketinggian
kolom udara 5 cm.
3. Getarkanlah garputala di atas lampu neon yang terbuka.
4. Lakukan pemompaan terhadap air dari lampu neon
agar air keluar melalui selang dengan botol air mineral secara perlahan-lahan.
b. Resonansi pada Kolom Udara
(6B92D:<2?#/$#3 H2?8>6>A6B=:92D<2?A6B:CD:G2B6C@?2?C: A252<@=@>E52B2":<2<@=@>E52B2H2?8D6B=6D2<5:2D2CA6B>E<22?2:B 5:86D2B<2? 56?82? >6?88E?2<2? C63E29 82BAED2=2 >@=6<E=>@=6<E= E52B25:52=2><@=@>E52B22<2?:<ED36B86D2B*H2B2DD6B;25:?H2B6C@?2?C: A252<@=@>E52B2252=29
D6A2DA252A6B>E<22?2:B92BECD6B36?DE<B2A2D2? C:>AE=86=@>32?8 A252E;E?8A6B>E<22?<@=@>E52B2>6BEA2<2?A6BED B6?882?82?
86=@>32?8
,?DE<>6?52A2D<2?B6C@?2?C:A2?;2?8<@=@>E52B25:2D2CA6B>E<22? 92BEC5:E329E32952AE?7B6<E6?C:52?A2?;2?886=@>32?83E?H:?H2D6D2A )6C@?2?C:A6BD2>22<2?D6B;25:;:<2A2?;2?8<@=@>E52B25:2D2CA6B>E<22? 2:B
B6C@?2?C:<65E2 B6C@?2?C:<6D:82 52?C6D6BEC?H2 *2>2 92=?H2 56?82? 86D2B2? E52B2 A252 A:A2 @B82?2 D6BDEDEA 9E3E?82?A2?;2?8<@=@>E52B2D6B9252AA2?;2?886=@>32?83E?H:
A252A6B:CD:G2B6C@?2?C:<@=2>E52B252A2D5:DE=:CC63282:36B:<ED
N
#6D6B2?82?
A2?;2?8<@=@>E52B2<6N
A2?;2?886=@>32?83E?H:
":<27B6<E6?C:82BAED2=25:<6D29E:46A2DB2>32D86=@>32?83E?H:82BAED2=2 52A2D 5:D6?DE<2? >6=2=E: A6BC2>22?$ 82B ?52 52A2D
>6?82A=:<2C:<2?AB@C6CA6?8E<EB2?46A2DB2>32D3E?H:5:E52B236B52C2B<2? <@?C6AB6C@?2?C:3E?H:A252<@=@>E52B2=2<E<2?=292<D:F:D2C36B:<ED
6B52C2B<2? 2<D:F:D2C D6BC63ED ?52 2<2? >6?52A2D<2? 52D2 A2?;2?8<@=@>E52B2#6>E5:2?3282:>2?2<2942B2>6?89:DE?846A2D B2>32D3E?H:5:E52B2(6B92D:<2?<6>32=:'34#/##09
?
":<2?52>6?89:DE?8C6=:C:9152?02<2?5:52A2D<2?
N
N
N
'=69<2B6?2A2?;2?886=@>32?8CE5295:<6D29E:?5252A2D>6?89:DE?8 46A2DB2>32D?H236B52C2B<2?A6BC2>22?
$ N
#6D6B2?82?
$ 46A2DB2>32D3E?H:> C
A2?;2?886=@>32?882BAED2=2>
7B6<E6?C:82BAED2=2 I
Nilai frekuensi setiap garputala sudah diketahui. Analoginya seperti nilai fokus dari lensa.
Ingatlah
5. Berhentilah memompa air pada saat terdengar bunyi mendengung. Ukur panjang kolom saat itu dan catat sebagai l1 (resonansi pertama) pada tabel pengamatan seperti berikut.
6. Turunkan permukaan air dalam lampu neon sampai terdengar bunyi mendengung lagi. Ukur panjang kolom saat itu dan catat sebagai l2
(resonansi kedua) pada tabel pengamatan.
7. Ulangi langkah tersebut sampai didapatkan l3, l4, dan seterusnya.
Data Pengamatan Resonansi Udara untuk Percobaan Cepat Rambat Udara
Resonansi ke–n Panjang Kolom Udara ( )
1. 2. 3.
.... .... ....
(25282>32BD2>A2<C63E29<@=@>E52B2H2?8A2?;2?8?H2E?DE< >6?892C:=<2?B6C@?2?C:<@=@>E52B2C642B2F6BD:<2=":<2<@=@>E52B2 D6BA6?56< >6?892C:=<2? B6C@?2?C: C22D 4> D6?DE<2?
7B6<E6?C:82BAED2=2
+6?DE<2?AE=2A2?;2?8<@=@>E52B2A252B6C@?2?C:C6=2?;ED?H2 :<6D29E:46A2DB2>32D3E?H:5:E52B2$> C
#7#$ :<6D29E:
4>>$> C
(252A6B:CD:G2B6C@?2?C:A6BD2>252=2><@=@>E52B236B=2<E9E3E?82?36B:<ED
2D2E
4> 4> >
Contoh
3.10
F. Energi Gelombang Bunyi
+6=29?52<6D29E:329G286=@>32?8252=2986D2B2?H2?8>6B2>32D >6=2=E:I2DA6B2?D2B2>65:E>D6D2A:>65:E>?H2D:52<:<ED>6B2>32D 2=2>A6B2>32D2??H286=@>32?8>6>:?529<2?6?6B8:52B:C2DED6>A2D <6D6>A2D=2:??6B8:86=@>32?83E?H:H2?85:D:>3E=<2?52B:CE2B2 A6C2G2D;6D!# !52A2D>6>6429<2?<242;6?56=2CE2DE32?8E?2? 2=D6BC63ED>6?E?;E<<2?329G26?6B8:86=@>32?83E?H:>6=2<E<2? A6B2>32D2? ?6B8: 86=@>32?8 3E?H: 52A2D 5:D6?DE<2? 52B: 6?6B8: A@D6?C:2=>2<C:>E>86D2B2?<2B6?23E?H:>6BEA2<2?86=@>32?8=@?8: DE5:?2=92C:=A6B2>32D2?86D2B2?'=69<2B6?2:DE6?6B8:86=@>32?8 3E?H:52A2D5:?H2D2<2?56?82?H2:DEC63282:36B:<ED
<2B6?2
Tes Kompetensi
Subbab
E
'3,#-#0.#*&#.#/$6-6.#5+*#0
(252C6ED2C52G2:H2?8A2?;2?8?H2>56?82?>2CC2 8A6B2>32D2?86=@>32?8DB2?F6BC2=H2?85:92C:=<2? >6>:=:<:<646A2D2?> C+6?DE<2?D682?82?52G2: D6BC63ED
+2=:H2?8A2?;2?8?H2>5:D682?8<2?56?82?82H2 &(6B2>32D2?86=@>32?8DB2?CF6BC2=H2?85:92C:=<2? >6>:=:<:<646A2D2?> C+6?DE<2?>2CC2D2=: D6BC63ED
E2ED2CD2=:H2?8C2>2A2?;2?85:D2B:<@=6982H2H2?8 C2>2%2CC2D2=:A6BD2>2<2=:>2CC2D2=:<65E2+2=: A6BD2>2 5:86D2B<2? 56?82? 7B6<E6?C: I C652?8<2?D2=:<65E2 I":<2A2?;2?886=@>32?8 A252D2=:A6BD2>24>D6?DE<2?A2?;2?886=@>32?8 A252D2=:<65E2
*63E2986=@>32?8C:?EC>6B2>32DA252D2=:H2?8 A2?;2?8?H24>36B86B2<52B:C:>A2?82?>:?:>E>
<6>2<C:>E>*E2DED:D:<>6>6B=E<2?G2<DE C6<@?52=2>86B2<D6BC63ED+6?DE<2?
2 A6B:@5686=@>32?8 3 7B6<E6?C:86=@>32?8
4 82H2D682?8D2=:;:<25:<6D29E:A2?;2?886=@>32?8
>52?>2CC2D2=:8B2>
*63E29 A:A2 @B82?2 D6B3E<2 A2?;2?8?H2 4> +6?DE<2?7B6<E6?C:?25252C2BH2?85:92C:=<2?A:A2 D6BC63ED;:<246A2DB2>32D3E?H:5:E52B2> C *63E29A:A2@B82?2D6BDEDEAA2?;2?8?H24>
+6?DE<2??25252C2BH2?85:92C:=<2?A:A2:DE;:<246A2D B2>32D3E?H:5:E52B2> C
+6?DE<2?A2?;2?8>:?:>E>A:A2@B82?2D6B3E<2H2?8 36B6C@?2?C:56?82?82BAED2=2H2?836B86D2B56?82? 7B6<E6?C: I;:<246A2DB2>32D3E?H:5:E52B2 > C
Kata Kunci
• resonansi• Hukum Mersenne • pipa organa • Hukum I Bernoulli • Hukum II Bernoulli
> C I>
$
"25:7B6<E6?C:82BAED2=2252=29 I
(2?;2?8<@=@>E52B2A252B6C@?2?C:<65E252?<6D:8252A2D5:D6?DE<2?
56?82?'34#/##09 H2:DE
52?E?DE<B6C@?2?C:<65E2 252=29
> >
"25:E?DE<B6C@?2?C:<6D:82 > m
Gambar 3.15
Sumber bunyi berupa titik. Semakin jauh dari sumber bunyi, luas permukaan semakin besar.
P r
1 r2
2D2E
>2<25:A6B@=69
N
#6D6B2?82?
>2CC2A2BD:<6=<8
2>A=:DE5@86=@>32?8>
7B6<E6?C:86D2B I
<@?CD2?D2A682C& >
6B52C2B<2?'34#/##09 6?6B8:H2?85:A:?529<2?@=69CE2DE 86=@>32?8C632?5:?856?82?<E25B2D2>A=:DE5@?H2
1. Intensitas Gelombang Bunyi
!?D6?C:D2C86=@>32?83E?H:5:567:?:C:<2?C63282:;E>=296?6B8:3E?H: A6BC2DE2?G2<DEH2?8>6?6>3ECD682<=EBECCE2DE3:52?8A6BC2DE2? =E2C E3E?82? 2?D2B2 52H2 =E2C 52? :?D6?C:D2C 3E?H: >6>6?E9:A6BC2>22?
N #6D6B2?82?
:?D6?C:D2C86=@>32?83E?H:- >
=E2CA6?2>A2?8>
52H286=@>32?83E?H:-*E>36B3E?H:36BEA2C63E29D:D:<C6A6BD:A252#/$#3 2<2? >6>2?42B<2?3E?H:<6C682=22B29BD:?H286=@>32?83E?H:>6B2>32D 52=2>D:825:>6?C: 2=H2?8C2>2D6B;25:AE=2A25286=@>32?84292H2 !?D6?C:D2C3E?H:A2523:52?8A6B>E<22?52=2>3@=2H2?8>6>:=:<:;2B: ;2B: 2<2?>6>:=:<:=E2C 2?882AD:52<2526?6B8:3E?H:H2?8
9:=2?82D2ED6BC6B2AC6=2>2A6B2>32D2?
!?D6?C:D2C3E?H:2<2?C6>2<:?<64:=;:<2;2B2<CE>36B3E?H:<6CE2DE 3:52?8A6B>E<22?C6>2<:?;2E9(6?8EB2?82?:?D6?C:D2C3E?H:2<:32D A6BD2>3292?;2B2<52B:CE>36B3E?H:>6>6?E9:9E3E?82?36B:<ED
N
#6D6B2?82?
;2B2<CE>36B3E?H:<6A@C:C:3:52?8> ;2B2<CE>36B3E?H:<6A@C:C:3:52?8>
6B52C2B<2?'34#/##09 52A2D5:?H2D2<2?329G2:?D6?C:D2C 3E?H:36B32?5:?8D6B32=:<56?82?<E25B2D;2B2<CE>36B3E?H:D6BC63ED <63:52?8A6?56?82B2?
2. Taraf Intensitas (TI)
*6D:2A >2<9=E< 5: 2=2> C6>6CD2 :?: >6>:=:<: 32D2C :?D6?C:D2C A6?56?82B2?2D2C:?D6?C:D2C3E?H:H2?852A2D5:56?82BD6=:?82>2?EC:2 252=29C63282:36B:<ED
1 bel (B) = 10 desibel (dB)
Ingatlah
Tugas Anda 3.4
+2B27:?D6?C:D2C3E?H:C63E29A6C2G2DA252;2B2<>252=2956B2A2D2B27 :?D6?C:D2C3E?H:A252;2B2<>
#7#$
:<6D29E: >>5
!?D6?C:D2C3E?H:36B32?5:?8D6B32=:<56?82?<E25B2D;2B2<
56?82?>6?88E?2<2?'34#/##09 E?DE<52?5:A6B@=69
=@8
=@8
=@8 =@8
Suatu gelombang gempa terasa di Malang dengan intensitas 6 × 105 W/m2.
Sumber gempa berasal dari suatu tempat yang berjarak 300 km dari Malang. Jika jarak antara Malang dan Surabaya sebesar 100 km dan ketiga tempat itu membentuk segitiga siku-siku dengan sudut siku-siku di Malang, maka intensitas gempa yang terasa di Surabaya adalah .... a. 2 × 105 W/m2
b. 3 × 105 W/m2
c. 4,5 × 105 W/m2
d. 5,4 × 105 W/m2
e. 7,5 × 105 W/m2
UMPTN 1996 Pembahasan:
2 2 2 1 1
2 1 1 2 2
I r r
I I
I r r
2 5
2 5
300 6 10
10
I
= 5,4 × 105 W/m2
Jawaban: d
Surabaya Malang sumber gempa
300 km
100 km
Contoh
3.11
Pembahasan Soal
2 !?D6?C:D2C D6B<64:= H2?8 >2C:9 52A2D >6?:>3E=<2? B2?8C2?82? A6?56?82B2?A252D6=:?82252=29C636C2BNG2DD >H2?85:C63ED
C63282:"!"!
3 !?D6?C:D2CD6B36C2BH2?8>2C:9>2>AE5:D6B:>2D6=:?82>2?EC:2D2?A2B2C2 C2<:D252=29C636C2BG2DD >H2?85:C63ED"!
"25:32D2CA6?56?82B2?D6B6?529252=29 N G2DD >52?32D2C
:?D6?C:D2CD6BD:?88:252=29G2DD >+2B27:?D6?C:D2CC632?5:?856?82?
=@82B:D>2A6B32?5:?82?2?D2B2:?D6?C:D2C3E?H:52?92B822>32?8:?D6?C:D2C 3E?H:H2?8D6B56?82B52?>6>:=:<:C2DE2?56C:36=5*642B2>2D6>2D:C 9E3E?82?2?D2B252?5:DE=:C
=@8
N
#6D6B2?82?
D2B27:?D6?C:D2C5
:?D6?C:D2C3E?H:- >
N- >:?D6?C:D2C2>32?8A6?56?82B2?
6B:<ED:?:52D2:?D6?C:D2C52?D2B27:?D6?C:D2C52B:3636B2A2CE>36B 3E?H:
>32?8A6?56?82B2? QN
>32?8B2C2C2<:D
*:B:?6A252;2B2<> QN
$2=E=:?D2CB2>2: QN
(6B42<2A2?3:2C2A252;2B2<4> QN
)25:@A6=2? QN
:C:<3:C:< QN
#$'.
!?D6?C:D2C52?+2B27!?D6?C:D2C52B:636B2A2*E>36BE?H:
05'04+5#4"/ 6/$'3608+ #3#(05'04+5#4&
*63E29CE>36B3E?H:>6?892C:=<2?D2B27:?D6?C:D2CC636C2B56B2A2D2B27 :?D6?C:D2CH2?85:92C:=<2?;:<2D6B52A2DCE>36B3E?H:H2?8C2>252?36B3E?H: A252C22D36BC2>22?
#7#$
:<6D29E:5
,?DE<C63E29CE>36B3E?H:
=@8
=@8
,?DE<3E29CE>36B3E?H:
Q
>2<2+! =@8
=@8
=@85
Contoh
3.12
":<2 D6B52A2D CE>36B 3E?H: H2?8 =63:9 52B: C2DE D2B27 :?D6?C:D2C D@D2=?H252A2D5:<6D29E:56?82?>6?88E?2<2?A6BC2>22?36B:<ED
?=@8 N
#6D6B2?82?
D2B27:?D6?C:D2C@=693E29CE>36B
32?H2<?H2CE>36B
D2B27:?D6?C:D2C@=693E29CE>36B
=@8
=@8
=@8
5=@8N5
"25:D2B27:?D6?C:D2C3E?H:A252;2B2<>252=295
Kata Kunci
• energi gelombang bunyi • intensitas gelombang • taraf intensitas• batas ambang pendengaran
*63E29CE>36B3E?H:>6>:=:<:D2B27:?D6?C:D2CC636C2B 5":<23E29CE>36B3E?H:H2?8C2>236B3E?H: C6B6?D2<36B2A2D2B27:?D6?C:D2C3E?H:H2?85:92C:=<2? 6B2A2A6B32?5:?82?:?D6?C:D2C5E2CE>36B3E?H:;:<2
D2B27:?D6?C:D2C?H25
*63E29CE>36B3E?H:D:D:<56?82?52H2G2DD >6>2?42B<2?86=@>32?83E?H:36BEA286=@>32?8 C76B:C3@=2+6?DE<2?D2B27:?D6?C:D2C3E?H:H2?8 5:56?82B@=69C6C6@B2?8A252;2B2<>6D6B52B: CE>36B3E?H:D6BC63EDNG2DD >
*63E29CE>36B3E?H:>6>:=:<:D2B27:?D6?C:D2C36== ":<23E29CE>36B3E?H:H2?8C2>236B3E?H:C642B2 C6B6?D2< 36B2A2<29 D2B27 :?D6?C:D2C 3E?H: H2?8 5:92C:=<2?
$5#0#4 *63E29CE>36B3E?H:>6>2?42B<2?6?6B8:<6C682=2 2B29A23:=2;2B2<A6?56?82BD6B9252ACE>36B3E?H: 5:3E2D>6?;25:<2=:C6>E=236B2A2A6?8EB2?82?D2B27 :?D6?C:D2C3E?H:H2?8D6B56?82B
Tes Kompetensi
Subbab
F
Rangkuman
6=@>32?83E?H:252=2986=@>32?8=@?8:DE5:?2=H2?8 52A2D>6B2>32D52=2>>65:E>I2DA252D42:B52?82C 6A2DB2>32D3E?H:5:E52B236B82?DE?8A252;6?:C A2BD:<6=A6>36?DE<E52B2H2?85:?H2D2<2?56?82?
$
C652?8<2?5:52=2>I2DA252D36B82?DE?8A252 >@5E=EC.@E?852?>2CC2;6?:CI2D
$
52AE?5:52=2>I2D42:B36B82?DE?8A252>@5E=EC E=<52?>2CC2;6?:CI2D42:B
$
+:?88:B6?529?2523E?H:36B82?DE?8A2527B6<E6?C: 3E?H:#E2D3E?H:36B82?DE?8A2522>A=:DE5@86D2B2? E5:@C@?:<252=293E?H:H2?836B7B6<E6?C:2?D2B2 IC2>A2:56?82? I!?7B2C@?:<252=29 3E?H:H2?836B7B6<E6?C:5:32G29 IC652?8<2? E=DB2C@?:<252=293E?H:H2?836B7B6<E6?C:5:2D2C I
6=@>32?83E?H:52A2D>6?82=2>:AB@C6C5:CA6BC: B67B2<C:B67=6<C:5:7B2<C::?D6B76B6?C:52?A@=2B:C2C: !?D6B76B6?C:86=@>32?83E?H:D6B;25:;:<23652=:?D2C2?
86=@>32?8?H2>6BEA2<2?<6=:A2D2?3:=2?82?3E=2D 52B:C6D6?829A2?;2?886=@>32?83E?H:
!
(6BC2>22?CEA6BA@C:C:86=@>32?83E?H:
4@C C:?
& " "
B6<E6?C:52??25252C2BA25252G2:5:?H2D2<2?56?82?
A6BC2>22?
C652?8<2?7B6<E6?C:?2522D2C<6A25252G2: 5:?H2D2<2?56?82?A6BC2>22?
(252A:A2@B82?2D6B3E<27B6<E6?C:?2522D2C<6
5:?H2D2<2?56?82?A6BC2>22?
$
C652?8<2?A252A:A2@B82?2D6BDEDEA7B6<E6?C:?252 2D2C<65:?H2D2<2?56?82?
$
E3E?82? A2?;2?8 <@=@> E52B2 D6B9252A
A2?;2?8 86=@>32?8 3E?H: A252 A6B:CD:G2
B6C@?2?C:<@=@>E52B2252=29
2=2>A6B2>32D2??H286=@>32?83E?H:>6>:?529 <2?6?6B8:C636C2B
& 56?82?&252=29
2>A=:DE5@86=@>32?8
*6>2<:?;2E9;2B2<CE>36B3E?H:D6B9252AA6?56?82B :?D6?C:D2C3E?H:2<2?C6>2<:?<64:=
!?D6?C:D2C3E?H:5:?H2D2<2?56?82?A6BC2>22?
=@8
":<2D6B52A2D3E29CE>36B3E?H:D2B27:?D6?C:D2C 3E?H:D@D2=?H25:?H2D2<2?56?82?A6BC2>22?
Peta Konsep
#=2C:7:<2C: 6=@>32?8E?H:
6A2D)2>32D *:72D*:72D
6=@>32?8E?H:
/2D(252D
$
/2D2:B
$
2C
$
!?D6B76B6?C:
(6>2?DE=2?
:7B2<C:
(6=2H2?82?
!?D6?C:D2CE?H:
+2B27!?D6?C:D2C
;:<2CE>36B 3E?H:?H232?H2< >6>3292C
'.1/$#0)608+
>6>3292C
=@8
>6>3292C
+:?88:E?H:
#E2DE?H: -2B?2E?H:
Setelah mempelajari bab ini, Anda tentu dapat mengetahui sifat-sifat dasar gelombang bunyi dan klasifikasi gelombang bunyi serta dapat menjelaskan peristiwa resonansi pada pipa organa. Dari materi bab ini, bagian manakah yang Anda anggap sulit? Coba diskusikan dengan teman atau guru Fisika Anda.
Refleksi
Pada bab ini pula, Anda telah mempelajari manfaat dari gelombang bunyi, seperti untuk mengukur kedalaman laut. Coba Anda sebutkan manfaat lain yang Anda rasakan setelah mempelajari bab ini.
(252CE2DEC22DD6B=:92D<:=2D52?56D:<<6>E5:2? D6B56?82BCE2B28E?DEB?H2":<236C2B<646A2D2? 4292H2Q> C52?<646A2D2?3E?H:> C ;2B2<2?D2B2D6>A2D2C2=<:=2D52?A6?82>2D
2 > 5 Q>
3 > 6 Q>
4 >
*63E29 2=2D C@?2B 5:8E?2<2? E?DE< >6?8E<EB <652=2>2?=2ED*6=2?8G2<DEH2?85:42D2D@=69C@?2B E?DE<86=@>32?8>6B2>32D9:?882<6>32=:=28:<6 C@?2B252=29C6<@?":<246A2DB2>32D86=@>32?85: 52=2>2:B=2ED252=29> C<652=2>2?=2ED D6BC63ED252=29
2 > 5 >
3 > 6 >
4 >
E23E29CE>36B3E?H:C6A6BD:D2>A2<A25282>32B 36B:<ED36B86D2BC642B2<@96B6?E?H:H2?8?H2B:?8 5:92C:=<2?5:;:<2 6?82?>6?2:<<2?C642B2 A6B=292?=292?3E?H:D6B=6>295:56?82B<6D:<2N 252=294>4>52?4>":<246A2DB2>32D 3E?H:5:E52B2> C36C2B7B6<E6?C:3E?H:252=29
2 I 5 I
3 I 6 I
4 I
E23E29#! 52?5:=6D2<<2?C6A6BD:A252 82>32B36B:<ED+6B?H2D2A25256D6<D@BD6B;25: :?D6B76B6?C:>2<C:>E>@B56A6BD2>2":<2<646A2D2? 3E?H:5:E52B2> C7B6<E6?C:86=@>32?83E?H: D6BC63EDD6BC63ED252=29
2 I 5 I
3 I 6 I
4 I
%@5E=ECE=<CE2DEI2D42:BH2?8>6>:=:<:>2CC2;6?:C 8B2> 4>252=29Q& >6A2DB2>32D 86=@>32?852=2>I2D42:BD6BC63ED252=29
2 > C 5 > C
3 > C 6 > C
4 > C
*63E29CE>36B3E?H:36B7B6<E6?C:< I36B86B2< =2?8CE?8<62B29C6@B2?8A6?56?82B56?82?<6=2;E2? <2=: <6=2;E2? 3E?H: B6<E6?C: 3E?H: H2?8 5:D6B:>2?H2252=29
2 < I 5 < I
3 < I 6 < I
4 < I
1#.!9! ?52C652?836B86B2<>6?56<2D:C63E29CE>36B3E?H: *D:52<36B86B2<H2?836B252;2E95:56A2??5252? C652?8>6>2?42B<2?3E?H:36B7B6<E6?C:<6C682=2 2B2982<;2E95:36=2<2?8?52D6B52A2DC63E29 5:?5:?8 A6>2?DE= E?H: H2?8 ?52 56?82B =2?8CE?852B:*56?82?7B6<E6?C:C52?H2?836B2C2= 52B: A2?DE=2? 5: 56?82? 7B6<E6?C:5<6D:<2 36B:?D6B2<C:5:D6=:?82?52252=29
2 D:52<2<2?>6?:>3E=<2?=2H2?82?<2B6?2
C5
3 D:52<2<2?>6?:>3E=<2?=2H2?82?<2B6?2
C5
4 2<2?>6?:>3E=<2?=2H2?82?52?>6>6?E9:
C5
5 2<2?>6?:>3E=<2?=2H2?82?52?>6>6?E9:
C5
6 2<2?>6?:>3E=<2?=2H2?82?52?>6>6?E9:
C5
*63E29CE>36B3E?H:36B86B2<56?82?<646A2D2?> C >6?E;E<6A6?56?82BH2?85:2>C69:?8827B6<E6?C: H2?85:56?82B@=69A6?56?82B252=29":<2CE>36B 3E?H:D6BC63ED5:2>C652?8<2?A6?56?82B36B86B2< 56?82?<646A2D2?> C>6?56<2D:CE>36B3E?H: 7B6<E6?C:H2?85:56?82B@=69A6?56?82B252=29":<2 46A2DB2>32D3E?H:5:E52B2$> CA6B32?5:?82? 252=29
2 5 N$
3 N$ 6 $
4 $
*6@B2?8A6?6B32?8H2?8A6C2G2DD6B32?8?H2>6?E;E <6>6?2B232?52B2>6?56?82B3E?H:C:B:?6>6?2B2 56?82?7B6<E6?C: I":<2C22D:DEC:B:?6D6BC63ED >6>2?42B<2?3E?H:56?82?7B6<E6?C: I52? 46A2DB2>32D3E?H:5:E52B2> C<646A2D2? A6C2G2DD6B32?8D6BC63ED252=29
2 <> ;2> 5 <> ;2> 3 <> ;2> 6 <> ;2> 4 <> ;2>
S
S2
r1
r2
P
40 m A
B 9 m
D
Tes Kompetensi
Bab 3
(6=2H2?82?3E?H:D6B;25:<2B6?2252?H2:?D6B76B6?C: 2 =63:952B:86=@>32?8H2?8C2>27B6<E6?C:?H2 3 86=@>32?8H2?836B=2G2?2?2B2986D2B?H2 4 86=@>32?8H2?8C2>27B6<E6?C:?H2 5 86=@>32?8H2?836C2B36527B6<E6?C:?H2 6 86=@>32?8H2?8<64:=36527B6<E6?C:?H2 ":<25E23E29CE>36B3E?H:>2C:?8>2C:?856?82?
7B6<E6?C: I52? I36B3E?H:C6B6?D2< 2<2?D:>3E=A6=2H2?82?3E?H:56?82?7B6<E6?C:
2 I 5 I
3 I 6 I
4 I
*6ED2C52G2:>6?892C:=<2?B6C@?2?C:A6BD2>2A252
4>":<2A2?;2?8<2G2D4>52?36B86D2B
A252?2522D2C<65E246A2DB2>32D86=@>32?8DB2?C F6BC2=52=2><2G2D252=2946A2DB2>32D3E?H:5: E52B2> C
2 > C 3 > C 4 > C 5 > C 6 > C
E23E2952G2:32;2H2?8:56?D:<>6>36B:<2??252 52C2B56?82?7B6<E6?C: I":<2D682?82?52=2> C2=29C2DE52G2:5:D2>3297B6<E6?C:A6=2H2?82? H2?8D6B;25:252=29
2 I 5 I
3 I 6 I
4 I
*63E29D23E?886=2CB6C@?2?C:H2?836B:C:2:B>6>:=:<: =E2CA6?2>A2?84>(252A@C:C:D6BC63EDD6B;25: B6C@?2?C:A6BD2>2*6;E>=294>2:B5:3E2?8<6=E2B C69:?882D6B;25:B6C@?2?C:<65E2":<2<6=2;E2?3E?H: 5:E52B2> C7B6<E6?C:82BAED2=2H2?85:A2<2: 252=29
2 I 5 I
3 I 6
4 I
(252A6B4@322?%6=565:8E?2<2?C6ED2C36?2?8H2?8 A2?;2?8?H2>6D6B52?36B>2CC28B2>":<23632? C636C2B<85:82?DE?8<2?A25236?2?8D6BC63ED <646A2D2?A6B2>32D2?86=@>32?8A25236?2?8252=29 > C
2 > C 5 > C
3 > C 6 > C
4 > C
*6ED2C52G2:>6?892C:=<2??25252C2B":<252G2: D6BC63ED5:A6?56<<2?4>D2?A2>6?8E329D682?82? 5:92C:=<2?7B6<E6?C:":<252G2:5:A6?56<<2? 4>=28:7B6<E6?C:H2?85:92C:=<2?252=29
2 5
3 6
4
*6ED2C52G2:H2?8A2?;2?8?H24>52?36B>2CC2 8B2>5:;6A:D<65E2E;E?8?H252?5:B6?D2?8<2?56?82? D682?82?&B6<E6?C:?2522D2CA6BD2>2H2?8 5:92C:=<2?252=29
2 I 5 I
3 I 6 I
4 I
1,2 m
f = 340 Hz
W
#6D:<2 82BAED2=2 5:86D2B<2? A252 52G2: D6B;25: 86=@>32?8CD2C:@?6BC6A6BD:D2>A2<A25282>32B #646A2D2?B2>32D86=@>32?8A25252G2:252=29
2 > C 5 > C
3 > C 6 > C
4 > C
*63E29A:A2@B82?2D6BDEDEA>6>:=:<:A2?;2?84> ":<246A2DB2>32D3E?H:5:E52B2> C36C2B7B6<E6?C: ?2522D2C<65E2252=29
2 I 5 I
3 I 6 I
4 I
&252 2D2C A6BD2>2 A:A2 @B82?2 D6B3E<2 H2?8 A2?;2?8?H24>36B6C@?2?C:56?82?A:A2@B82?2 D6BDEDEA":<2A252C22D36B6C@?2?C:;E>=29C:>AE=A252 <65E2A:A2C2>2A2?;2?8A:A2@B82?2D6BDEDEAD6BC63ED 52=2>4>252=29
2 5
3 6
4
! #810 (252A:A2@B82?2D6B3E<2?2522D2C<65E25:92C:=<2? A2?;2?886=@>32?8C636C2B%52?A252A:A2@B82?2 D6BDEDEA?2522D2C<65E25:92C:=<2?A2?;2?886=@> 32?8C636C2B&":<2A2?;2?8<65E2A:A2C2>2?:=2: A6B32?5:?82?&52?%252=29
2 3 4 5 6
+2B27:?D6?C:D2C3E?H:C63E29>6C:?B2D2B2D25 ":<2>6C:?5:9:5EA<2?36BC2>2D2B27:?D6?C:D2C?H2 252=29
*63E2982BAED2=236B7B6<E6?C: I5:86D2B<2?5: A6B>E<22?D23E?8B6C@?2?C:(252C22D<@=@>E52B2 >6?42A2:<6D:?88:2?4>D6B;25:B6C@?2?C:H2?8 A6BD2>26B2A2<2946A2DB2>32D3E?H:C22D:DE *6ED2C<2G2DH2?8A2?;2?8?H24>5::<2D<65E2
E;E?8?H2#6>E5:2?<2G2D5:86D2B<2?=@?8:DE5:?2= 6A2DB2>32D86=@>32?8H2?85:92C:=<2?> C %@5E=EC.@E?8<2G2DQ& > :DE?8=29 2 7B6<E6?C:86D2B?H2
3 >2CC2;6?:C<2G2D
%@3:= >6?56<2D: A6?82>2D 5:2> 56?82? <646A2D2? > C C2>3:= >6>3E?H:<2? C:B6?6 36B7B6<E6?C: I(252C22D:DE;E82>@3:= >6?56<2D:52B:2B29H2?836B=2G2?2?56?82? A252<646A2D2?> CC2>3:=>6>3E?H:<2?C:B:?6 36B7B6<E6?C: I":<246A2DB2>32D3E?H:5:E52B2 C22D:DE> C36B2A2<297B6<E6?C:=2H2?82?H2?8 5:56?82B@=69
*6ED2C<2G2D32;2H2?8>2CC2?H2852?A2?;2?8> 5:36B:D682?82?&+6?DE<2?
2 46A2DB2>32DA2?;2?886=@>32?8DB2?CF6BC2= C6A2?;2?8<2G2D
3 A2?;2?886=@>32?852?7B6<E6?C:?25252C2B?H2 4 7B6<E6?C:?2522D2C<6C2DE52?<65E2
B6<E6?C:?2522D2CA6BD2>252B:A:A2@B82?2D6B3E<2 I":<246A2DB2>32D3E?H:5:E52B2> C 9:DE?8=29
2 7B6<E6?C:?25252C2B?H2 3 7B6<E6?C:?2522D2C<6D:82
6A2DB2>32D3E?H:52=2>C63E29A:A2@B82?2252=29 > C":<27B6<E6?C:?25252C2BA:A2@B82?2252=29 I36B2A2A2?;2?8>:?:>E>A:A2@B82?2E?DE< <2CEC
2 A:A2@B82?2D6B3E<2 3 A:A2@B82?2D6BDEDEA
E2ED2C52G2:32;2C6;6?:C>6>36B:<2??25252C2B I":<2A2?;2?8C2=29C2DE52G2:5:D2>329 36B2A2<297B6<E6?C:=2H2?82?H2?8D6B;25:
E2ED2C52G2:32;2H2?8:56?D:<>6>36B:<2??252 52C2B56?82?7B6<E6?C: I":<2D682?82?52=2> C2=29C2DE52G2:5:D2>32936B2A27B6<E6?C: =2H2?82?52G2:H2?8>E?8<:?
*66<@BD2G@?H2?8>6?56?8E?8A252;2B2<> >6>:=:<:D2B27:?D6?C:D2C5":<2252D2G@? >6?56?8E?8A252;2B2<%D2B27:?D6?C:D2C?H25 D6?DE<2?;2B2<%
(252C63E29D23E?8B6C@?2?C:D6B52A2D<@=@>E52B2 A252"*6=:C:9A2?;2?8<@=@>B6C@?2?C:4> #646A2D2?3E?H:A252CE9EL252=29> C :DE?8";:<27B6<E6?C:B6C@?2?C: I
#7#$.#*2'35#08##0$'3+-65&'0)#05'2#5 ":<2C63E29C6A652>@D@B>6=6G2D:C6C6@B2?8>@D@B
D6BC63ED2<2?>6?:>3E=<2?D2B27:?D6?C:D2C+!C636C2B 5":<2@B2?8D6BC63ED5:=6G2D:C6A652>@D@B;6?:C H2?8C2>2C6<2=:8ECD2B27:?D6?C:D2C?H2252=29
2 5 5 5
3 5 6 5
4 5
+2B27:?D6?C:D2C3E?H:C63E29>6C:?252=295 56?82?24E2?:?D6?C:D2C2>32?8A6?56?82B2?C636C2B N- >":<2D2B27:?D6?C:D2C5:52=2>BE2?8A23B:< H2?8>6?88E?2<2?C6;E>=29>6C:?D6BC63ED252=29 5;E>=29>6C:?H2?85:8E?2<2?252=29
2 5
3 6
4
+2B27:?D6?C:D2C3E?H:A252C63E29;6?56=2D6B3E<2 H2?8=E2C?H2>252=295":<2?:=2:2>32?8 3E?H:N- 4>52H22<ECD:<H2?8>2CE<>6=2=E: ;6?56=2D6BC63ED252=29
2 N
-3 N
-4 N
-5 N
