Problem 4.19

F.B.D. ของมวล m

จาก \(ΣF_{x}= 0\)

T₁T₂

\(\theta \theta T_{2}\cos \theta - T_{1}\cos \theta = 0\)

\(T_{2} = T_{1}\)

∴ กำหนดให้ \(T_{2} = T_{1} = T\)

mg

จาก \(ΣF_{y}= 0\)

\(T_{1}\sin \theta + T_{2}\sin \theta - mg = 0\)

\(Tsin\theta + Tsin\theta = mg\)

\(2Tsin\theta = mg\)

\(T =\frac{mg}{2\sin \theta}\;\blacksquare\)