Question

Giúp tiếp ạ!!

Answer 1

Chu kỳ dao động:

\(T=2\text{π }\sqrt{\dfrac{l_1+l_2}{g}}\Rightarrow T^2=\left(2\text{π }\right)^2=\dfrac{l_1+l_2}{g}=T^2_1+T_2^2\)

\(T'=2\text{π }\sqrt{\dfrac{l_1-l_2}{g}}\Rightarrow T'^2=\left(2\text{π }\right)^2\dfrac{l_1-l_2}{g}=T^2_1-T^2_2\)

\(\Rightarrow\left\{{}\begin{matrix}T^2_1+T^2_2=2,7^2\\T^2_1-T_2^2=0,9^2\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}T_1=2s\\T_2=1,8s\end{matrix}\right.\)