Page 30 - 機械群機械力學升學寶典
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ዚɢኪ
༆ ਗ਼ʱɢٙɽʃʿ˙Σ̈dνɨྡf ഈ
F=200N
45º
F y F x
y x
45º
ð F x = 200 × cos45° = 100 2 Nd 45º
F x = –200 × sin45° = −100 2 Nd 45º
精選範例 4 同步練習 4
νɨྡהͪ F = 100 2 Nd༊ਗ਼ F ɢʱ༆ νɨྡהͪ F = 500Nd༊ਗ਼ F ɢʱ༆މ
މ (1) ضુࠦʿٜۧુࠦʘɚʱɢ (2) ض (1) ضુࠦʿٜۧુࠦʘɚʱɢ (2) ض˥
˥̻ൿx ൿʿٜۧൿy ൿʘɚʱɢf ̻ൿx ൿʿٜۧൿy ൿʘɚʱɢf
F=100√2 N F=500N 3
45º C 4 4
3 3
4
A B ഈ
༆ (1) F ضુࠦʿٜۧુࠦٙʱɢʱй˸ F ʿ
//
F ڌͪ
ç
F = 100 2 × cos45° =100Nd 4 3
//
F = 100 2 × sin45° =100Nd 4 3
ç
(2) ਗ਼F ʿF Іʱ༆މF x e F y ΎΥԻу̙dνɨό
//
ç
4 3
F x = 100 × – 100 × =20Nd
5 5
3 4
F y = 100 × + 100 × =140Nd
5 5
20
BD111_CH02.indd 20 23/7/2021 14:56:52