Pendulums

Core Sentence / 核心句

Pendulum motion becomes approximately simple harmonic when a small-angle restoring torque is proportional to angular displacement.
$T_{simple}=2\pi \sqrt{\frac{L}{g}}$
$T_{physical}=2\pi \sqrt{\frac{I_{pivot}}{Mgd}}$
$T_{torsional}=2\pi \sqrt{\frac{I}{\kappa }}$

Watch Out / 易错点

simple/physical pendulum 的 SHM 结论依赖 small-angle approximation；$I$ 必须对应 pivot。

Mentioned In / 出现位置

• 第12次正课 · pendulums

Connected Notes / 连接

• Simple Harmonic Motion
• Torque
• Parallel-Axis Theorem