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1 如圖所示,用一螺旋起重機舉500N重之物件,螺旋之導程為1cm,假設不計摩擦力,則舉起該物件,應出之力為
A 16.7N
B 19.7N
C 2.65N
D 5N

W/F=2πR/L

500 × 1=2 × π × 30 × F

F=2.65(N)