Đáp án:
\(\begin{align}
& 1>C \\
& 2>D \\
& 3>D \\
& 4>B \\
& 5>B \\
& 6>D \\
& 7>A \\
& 8>B \\
& 9>A \\
\end{align}\)
Giải thích các bước giải:
\(\begin{array}{*{35}{l}}
\text{ }\!\!~\!\!\text{ } & 1>C \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 2>D:\Delta \varphi =k2\pi \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 3>D \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 4>B \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & F=-k.s=-m.\frac{g}{l}.l.\alpha =-m.g.\alpha \text{ }\!\!~\!\!\text{ } \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 5>B \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & a=-{{\omega }^{2}}.A.cos(\omega t+\varphi ) \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 6>D \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & T=2\pi \sqrt{\frac{l}{g}} \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 7>A \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 8>B \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & f=\frac{1}{2\pi }.\sqrt{\frac{g}{\Delta {{l}_{0}}}} \\
\text{ }\!\!~\!\!\text{ }\!\!~\!\!\text{ } & 9>A \\
\text{ }\!\!~\!\!\text{ } & {} \\
\end{array}\)
