r = acosωti + bsinωtjv = dr/dt = -aωsinωti + bωcosωtj角动量L = r×p = r×mv= m(acosωti + bsinωtj)×(-aωsinωti + bωcosωtj)= m(abωcos^2ωt + abωsin^2ωt)k= mabωk 常量质点所受对原点的力矩M...