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Chapter 2 x̻ࠦɢӻ
表 2-1 力的分解常見類型 (續)
圖形 公式 即時練習
ν̸ྡdW = 100Ndθ = 30°
= Wsinθ
W x
ۆ W x = –100 × sin30°
ᗳ θ = –50Nd 30º
ۨ θ W y W y = Wcosθ
y W y = –100 × cos30°
ɚ x W
θ W x θ
= −50 3 Nd
30º
ν̸ྡdண F = 100Ndθ = 45°
= Fcosθ
y x F x ۆ F x = 100 × cos45°
ᗳ θ
F = 50 2 Nd 45º
ۨ θ F y = Fsinθ = –100 × sin45°
ɧ F y F x F y
θ
θ = −50 2 Nd 45º
± ίᗳۨɚʿᗳۨɧʕdҢࡁਗ਼ضુࠦ٫່֛މ x ൿdٜۧુࠦ٫່֛މ y ൿf
搶分關鍵
Ϟࣛࡉᕚͦ݊л͜ᅰοુଟԸڌͪԉܓdνྡ 2-1 הͪdՉʱ༆˙جνɨj
˙ج 1 ᅺͪٙᅰοʕӋ̈ sinθ ʿ cosθdΎ˾ɝ W = Wsinθd
x
3
W = Wcosθ у ̙f Էj ν ྡ 2-1 ה ͪd ண W ࠠ W 4
y
100NdӋ W eW f 4 W y
y
x
y x 3
3 4 W x
༆ ͟ྡ̙ٝ sinθ = dcosθ = θ
5 5
圖 2-1
ð W x = –100 × sinθ = –60Nd 3
4
W y = –100cosθ = –80Nd 4
3
˙ج 2 ਗ਼ࡡᅺͪʘ˥̻ʿٜۧٙᅰο࿁ሜу̙dνɪྡהͪࡡᅺͪމ 3 dу˥̻
4
މ 4dٜۧމ 3dʦ૧Ӌʱɢසცਗ਼ضુࠦҷމ 3dٜۧુࠦҷމ 4dу 4 fᏑk
3
༆ ݂ W x = –100 × 3 = –60Nd 3 iW y = –100 × 4 = –80Nd 4
5 4 5 3
15
BD111_CH02.indd 15 23/7/2021 14:56:33