v=dr/dt=-awSin(wt)i+bwCos(wt)j
加速度A=dv/dt=-aw^2Cos(wt)i-bw^2Sin(wt)j
F=mA=-maw^2Cos(wt)i-mbw^2Sin(wt)j
M=r×F={aCos(wt)*[-mbw^2Sin(wt)]-bSin(wt)*[-maw^2Cos(wt)]}k
=0
L=r×mv={aCos(wt)*m[-awSin(wt)]-bSin(wt)*mbwCos(wt)}k
=-mw(a^2+b^2)Sin(wt)Cos(wt)k