阻尼振振
(阻尼正比於速度或是固體接觸面摩擦)
參考文章：
M.I. Molina, "Exponential Versus Linear Amplitude Decay in Damped Oscillators," Phys. Teach. 42, 485-487 (November 2004).
Martin Kamela, "An Oscillating System with Sliding Friction," Phys. Teach. 45, 110-113 (February 2007).
