普通物理学Ⅰ

equilibrium 平衡:

• translational(平动)：the net force acting on an object be zero(外力作用为0)
• rotational(转动)：the net torque about any point be zero(外力矩为0)

when something is rotational equilibrium:the net force will all pass a common point.(当某个物体处于转动平衡时，它所受到的外力将交于某一点)(3个非平行外力)

for a simple harmonic oscillator:\(\omega=\sqrt{k/m}\)
影响简谐振动振幅的因素：初始位置和初速度(initial position and initial velocity)

e.g.单摆
\(\Sigma F=\)