91
Dinamika Gerak
B. Penerapan Hukum Newton
252328:2?:?:?5222?6A6=2;2B:3636B2A2A6?6B2A2?9EE 6GD?52=269:5EA2?C692B:92B:
1. Gerak Benda pada Bidang Datar
,63E2936?52D6B=6D2A2523:52?852D2B=:4:?C6A6BD:A252 + 6E5:2? 5:36B: 82H2 6?52D2B 9:?882 36?52 36B86B2 =EBEC
56?82?A6B46A2D2? 2H282H2H2?8366B;2A252CE3E.252=29
.
, 6?52D:5236B86B2D6B9252ACE3E.22
.
, N
, 2H2H2?8366B;2A252CE3E-
-
Tes Kompetensi Subbab
A
, +22 1 , :DE?882H2H2?85:3EDE92?C63E293:=H2?82CC2
?H2
8E?DE6?42A2:646A2D2?
C52=2 G2DEC
,63E2982H2366B;2A25236?5236B2CC2 52?
A6B46A2D2?H2?85:D:3E=2?
C 2H2H2?8C22
366B;2A25236?52=2:?36B2CC2 A6B46A2D2?H2?8
5:D:3E=2?
C 2 6B2A229?:=2:B2C:
1 2
3 :2 52?
5:823E?836B2A2A6B46A2D2?H2?8 5:92C:=2?=6982H2
,63E293EC2CC2?H2 836B86B256?82?6 46A2D2?
;2 3:=5:B652?36B96?D:C6D6=29
6?6AE9;2B2
-6?DE2?82H2B6H2?8 366B;2A2523:=D6BC63ED
?52C652?836B2525:52=2C63E29A6C2G2DD6B32?8 A2526D:?88:2?
2: 6B2A2A6B
C6?29A6BE3292?36B2D3252??52 ,6AD?832DE32D2H2?82CC2?H2
8D6B=6D25:2
5:2D2CD2?29 6E5:2?32DED6BC63ED5:D2B:62D2C 56?82?82H2C6=22
C=2=E5:=6A2C2? :2
C D6?DE2? D:?88: 2C:E H2?8
5:42A2:?H2 ,63E293=236B2CC2
8B25::2DA252E;E?8
C6ED2CD2=:H2?8A2?;2?8?H24 =236BAED2B52 =2=:?82B2?9B:I?D2=56?82?6=2;E2?D6D2A
C
:DE?8D682?82?D2=: ,63E29A:B:?82?56?82?;2B:;2B:45:AED2B56?82?
646A2D2?CE5ED
B25
C -6?DE2?A6B46A2D2?52? 82H2C6?DB:A6D2=C63E29D:D:36B2CC2
8H2?836B252
5:A:?88:BA:B:?82?D6BC63ED ,63E29 3=2 36B2CC2
8 5:AED2B 6?8:D2B:
=:?82B2?F6BD:2=H2?8B25:EC?H256?82?=2;E C :DE?8D682?82?2C:E52?D682?82?:?:
E D2=: H2?8 6?89E3E?82? 3=2 6 AEC2D =:?82B2?;:2
C
,63E296?52B22?6?:E?85:=:?D2C2?;2=2?6? 52D2B2C2B56?82?;2B:;2B:6=6?8E?82?2CC2
6?52B22? 52? A6?EA2?8 8 -6?DE2? 646A2D2?2C:E282B6?52B2?D:52C=:A;:282H2
86C62?2?D2B232?52?;2=2? ,63E293:=6=6G2D:;2=2?463E?8 :6D29E:
B25:EC
2CC23:=36C6BD2A6?EA2?8?H2 8 2H2D62?3:=D6B9252A;2=2? :2
A6B46A2D2?8B2F:D2C:
C D6?DE2?=2;E3:=A252
C22D65E5E2?D6BD:?88:
Gambar 5.8
Gaya-gaya yang bekerja pada balok.
N F
w
92
Mudah dan Aktif Belajar Fisika untuk Kelas X
N 6D6B2?82?
A6B46A2D2?
C 82H2
2CC28
2523:52?852D2B=:4:?D:5225282H286C62?H2?8366B;22?D2B236?5256?82? 3:52?8 ,63E2936?5236B2CC28D6B=6D2A2526;26?52D2B=:4:? 6?52:DE
5:36B:82H26?52D2BC636C2B 6B2A2A6B46A2D2?36?52:DE 4
:6D29E: 8
8
C 25:A6B46A2D2?36?52
C
N
w F
= 10 N
,63E293:=36B2CC2
836B86B256?82?646A2D2?
;2 6B2A229 82H2H2?85:A6B=E2?E?DE6?86B6282B3:=36B96?D:A252;2B2
4 :6D29E:
8 +
;2
C 3:=36B96?D:36B2BD:+
+ N+
N
C N
C N
C
6?82? 6?88E?22?EE6GD?5:A6B=69
8N
C N
N7 25:282B3:=36B96?D:A252;2B2
92BEC5:6B;22?82H2C636C2BO
H2?82B29?H236B=2G2?2?56?82?2B2986B236?52
2. Gerak pada Bidang Miring
,63E2936?526:=::82H236B2D , D6B=6D2 A252 3:52?8 :B:?8=:4:?636?DECE5ED6:B:?82? D6B9252A82B:C9B:I?D2=
2H2H2?8366B;2A25236?52252=2982H2?B2= B2982H2?B2= D682=EBECD6B9252A3:52?8C6?DE9C6A6BD:A252 +
,E3E-C6;2;2B3:52?8:B:?852?CE3E.D682=EBEC3:52?8:B:?8 A?6?82H236B2DA252
CE3E-,
-
C:? CE3E.,
.
4C
Gambar 5.9
Gaya-gaya yang bekerja pada benda yang diletakkan pada
bidang miring mg
N
mg cos mg sin
licin
Sebuah balok bermassa 2 kg terletak di atas bidang datar licin. Pada balok
tersebut dikenakan gaya tarik dengan arah 60° terhadap arah
mendatar. Hitunglah percepatan balok tersebut.
Tantangan
untuk Anda Contoh
5.5
Contoh
5.6
93
Dinamika Gerak
N
v
mg cos
mg sin
mg
,6AD?832=H2?82CC2?H2
85:=E?4EB2?,EC2?DA2523:52?8:B:?8=:4:?D2?A2 646A2D2?2G2= ,E5ED6:B:?82?3:52?8D6B9252A9B:I?D2=J :2
C
36B2A229 2 82H2?B2=A25232=
3 646A2D2?32=C6D6=296=E?4EBC6=22C 4
:6D29E: 8
J C
2 A?6?82H236B2DA252CE3E. ,
.
,4C 4CJ
8
C 6?52D:5236B86B262B29CE3E.C69:?882
-
,
H
25:82H2?B2=?H2252=2910 3 3 A?6?82H236B2DA252CE3E-
,
-
,C:? C:?J
8
C 6?5236B86B2C6A2?;2?8CE3E-3:52?8:B:?8C69:?882
-
,
-
4C N
+6CE=D2?82H282H2A252CE3E-252=29
-
C:? C:?
6D6B2?82? 82H2?B2=
2CC236?528 CE5ED6:B:?82?
A6B46A2D2?8B2F:D2C:
C N
2H282H2H2?8366B;2A252CE3E.252=29
.
N,
.
4C 6?52D:5236B86B2D6B9252ACE3E.22
y
F
Contoh
5.7
Perhatikan perubahan pada Contoh 5.7.
Jika sudut diubah
menjadi 60°, berapakah gaya normal pada balok tersebut dan berapakah
kecepatan balok setelah meluncur selama 3 sekon? Buatlah kesimpulan
tentang perubahan sudut
terhadap gaya normal dan kecepatan benda.
Tantangan
untuk Anda
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