■解答
① \(mgl(2-\cos\theta_1)\) ② \(\sqrt{2gl(\cos \theta_2- \cos\theta_1)}\) ③ \(\cos \theta_2\)
④ \(\sin \theta_2\) ⑤ \(\sqrt{\displaystyle\frac{2l}{g}}\) ⑥ \(2l\sqrt{1-\cos\theta_1}\)
⑦ \(l\sin \theta_1\) ⑧ \(\displaystyle\frac{v_y}{g}+\sqrt{\frac{v_y^2}{g}+\frac{2l}{g}(2-\cos\theta_2)}\) ⑨ \(l\sin\theta_2\)
⑩ イ
