1/ Xét trong 1 chu kì, v=\frac{4A}{T}=\frac{4A\omega }{2\pi}=\frac{2v_{max}}{\pi}
2/ Ta có: x^{2}+\frac{v^{2}}{^{\omega ^{2}}}=A^{2}
\Rightarrow A=5 cm
Xét lúc t=0, có
\left\{\begin{matrix} x=Acos(\varphi )\\ v=-A\omega sin(\varphi ) \end{matrix}\right.
\Rightarrow \left\{\begin{matrix}...