Em cần cách giải ạ

\(\omega=\sqrt{\dfrac{k}{m}}=\sqrt{\dfrac{100}{0,1}}=10\pi\\A^2=x^2+\dfrac{v^2}{\omega^2}=1^2+\dfrac{(10\pi\sqrt{3})^2}{(10\pi)^2}=4\\\Rightarrow A=2(cm)\\\Delta l=\dfrac{mg}{k}=\dfrac{0,1.10}{100}=0,01(m)=1(cm)\\\begin{cases} t_n=\dfrac{\cos\left(\dfrac{-\Delta l}{A}\right)}{360}.T=\dfrac{T}{3}\\t_g=T-\dfrac{T}{3}=\dfrac{2T}{3}\end{cases}\Rightarrow \dfrac{t_n}{t_g}=\dfrac{\dfrac{T}{3}}{\dfrac{2T}{3}}=\dfrac{1}{2}\\\longrightarrow D.\)