86
Mudah dan Aktif Belajar Fisika untuk Kelas X
2H252?A6B46A2D2?252=2936C2B2?F6DBC652?82?2CC236?52 252=2936C2B2?C2=2B =692B6?2:DE82H25:DE=:CC63282:36B:ED
6D6B2?82? 82H2H2?8366B;2A25236?52
2CC236?528 A6B46A2D2?36?52
C
2=2,C2DE2?82H2252=298
C 5:C63ED;E82?6GD? .
,5:567:?:C:2?C63282:.. N
,63E2936?5236B2CC2
836B86B256?82?646A2D2?2G2=
C5:2D2C3:52?852D2B =:4:?6E5:2?36?52D6BC63ED5:36B:82H2D6D2AC62B2956?82?86B236?52 ,6D6=29
6?6AE9;2B2646A2D2?36?526?;25:
C -6?DE2?36C2B82H2D6BC63ED 4
:6D29E: +
C 8
+ C
6BC222?86B2 +
N+
N + +
C N
C
C
3. Hukum III Newton
2D2?C6ED2CD2=:A25232D2?8A9?6B2D6B2D282BD2=:D:52=6A2C C6A6BD:A252 +
682?8D2=:A252;2B23636B2A26D6B:B:?8
2?DE3E9?52C23:=6?2B:D2=:H2?8CE529D6BA2C2?8 ?52D:52 ;2DE93E2?2CEC:?:5:D2?82A=696GD?56?82?6?H2D22?329G2
. .
..,
2526;25:2?D6BC63ED2525E282H2H2?836B=2G2?2?H2:DE82H2D2B: =69 2?2 D6B9252A A9? 5:C63ED . C652?82? A9?
6A6BD292?2?2?256?82?82H2H2?8C225:C63ED. ,62:? 36C2B82H22C:H2?85:6?22?D6B9252AA9?C62:?36C2B82H2B62C:
H2?85:36B:2?A9? N
2H22C:52?82H2B62C:366B;2A2525E236?52H2?836B365256?82? 2B2936B=2G2?2?
6B92D:2? +
EE5:D2B:E:,F6BD:2=632G29 H2?836C2B?H2C636B2D3EE 6;2636B:2?82H25B?86A252
3EEH2?8C2236C2B56?82?82H28B2F:D2C:E:,C69:?882;E=29 65E282H2H2?8366B;2A2523EEC2256?82??= 82BD:52C2=29
A6BC6AC:65E282H2D6BC63ED3E2?A2C2?82?2C:B62C:2B6?2D:52 366B;2A25236?52H2?836B3652
Gambar 5.3
Putut menarik tali yang diikatkan pada pohon.
Contoh
5.1
6?EBEDEE6GD? 8
C
8
C 25:82H2H2?8366B;2A25236?52252=29
4 m
F v
m = 2 kg
Gambar 5.4
Gaya aksi dan gaya reaksi terjadi pada buku dan meja.
N
gaya tekan meja pada buku
gaya tekan meja pada buku
gaya reaksi
w
gaya gravitasi Bumi pada
buku gaya tekan
buku pada meja
gaya aksi
F
F
F F
F
= gaya tarik pohon terhadap
anak
F
,
= gaya tarik anak
terhadap pohon
Sebuah palu bermassa 2 kg diayunkan vertikal ke bawah dengan
kecepatan 20 ms. Palu tersebut menghantam sebuah paku,
mengakibatkan paku masuk sedalam 5 cm ke dalam kayu. Hitunglah gaya
hantam palu.
Tantangan
untuk Anda
87
Dinamika Gerak
252 +
3EE6?62?6;2C69:?882636B:2?82H2 2C:H2?82B29?H2632G29 ,63282:B62C:?H26;26?62?3EEH2?8
2B29?H262D2CC69:?882636B:2?82H2B62C: 65E282H2:?: 36C2B?H2C2252?36B=2G2?2?2B29C6BD2 366B;2A2525E236?52H2?8
36B3652 =692B6?2:DEA2C2?82?82H2:?:6BEA22?A2C2?82?2C: B62C:
6C:?DEB3A6C2G2D636B:2?82H22C:6=2=E:82C3E2?86328:2? 36=22?8 ,632=:?H2C63EB2?82C3E2?8B6D6?892C:=2?82H2B62C:
H2?86?H63232?A6C2G2DD6B5B?8656A2?2B6?22CC282C3E2?8 C2?82D64:= 2CD6BC63ED6?H63EB636=22?856?82?646A2D2?D:?88:
2H22C:52B:6C:?DEB36C:?A6C2G2DC2236C2B?H256?82?82H2B62C: 52B:C63EB2?82CD6D2A:2B29?H236B=2G2?2?
4. Gaya Berat
6D:2?526=6A2B2?E2?8=8262D2C2A2H2?8D6B;25: .2?8=82D6BC63ED22?36B86B2?2:9:?8826D:?88:2?2C:E
6E5:2?E2?8=82D6BC63ED22?;2DE9632=:6E: :2?52 6=6A2C2?E2?8=8252B:6D:?88:2?D6BD6?DE52B:D2?29E2?8=82
D6BC63ED;E8222?;2DE96E: .2?8=8222?C6=2=E;2DE96E: 56?82?A6B46A2D2?D6BD6?DE2B6?2252?H282H28B2F:D2C:E:A252E2?8
=82 ,6E236?5222?6?82=2:A6B46A2D2?H2?8C22D2?A25:A6?82BE9:
2CC2?H2 ?52?222?A6B46A2D2?:?:56?82?A6B46A2D2?8B2F:D2C: H2?836C2B?H2
C
52?5:=232?82?56?82? 2B: EE 6GD? H2?8 D6=29 ?52 A6=2;2B: ?52 52A2D
6?E=:C2?82H28B2F:D2C:
8
A25236?5236B2CC2C63282:36B:ED
8
6?82?6?88E?22? 52?6?E=:C2??H2E?DE82H28B2F:D2C: 5:A6B=69
4
Gambar 5.5
Gaya aksi dan gaya reaksi terjadi pada mesin turbo pesawat.
turbin digerakkan oleh gas panas
bahan bakar terbakar di dalam bilik bakar
baling-baling meniup udara ke
sekeliling mesin
aliran udara kompresor tahap kedua
meningkatkan tekanan kompresor tahap
pertama menekan udara masuk
buangan jet
N 6D6B2?82?
482H236B2D?6GD? 2CC236?528
A6B46A2D2?8B2F:D2C:
C
Massa dan berat bukan besaran yang sama. Satuan massa adalah kg dan
satuan berat adalah newton.
Ingatlah
:2A6B46A2D2?8B2F:D2C:5:?D:2?2
C 36B2A236B2D36?52H2?82CC2?H28
5:?D:2?2
4
:6D29E: 8
C
Contoh
5.2
