Problem 4.22

F.B.D. ของวัตถุมวล m

จาก \(ΣFT_{1}T_{2}^{x}= 0\)

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

\(\theta\)

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

∴ กำหนดให้ \(T_{2} = T_{1} = T\)

mg

จาก \(ΣF_{y}= 0\)

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

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

\(2Tsin\theta = mg\)

\(\ell\)

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

\(\sqrt{\ell ^{2} - (\frac{L}{2})^{2}}\)

\(\theta\)

\(T =\frac{mg}{2 1 - (\frac{L}{2\ell})^{2}}\;\blacksquare\)

\(\frac{L}{2}\)