Câu 53:
Tại \(t = \dfrac{1}{3}s\):
\(\begin{array}{l}
x = 6\sin \left( {\pi .\dfrac{1}{3} + \dfrac{\pi }{2}} \right) = 3cm\\
v = 6\pi \cos \left( {\pi .\dfrac{1}{3} + \dfrac{\pi }{2}} \right) = - 3\pi \sqrt 3 cm/s
\end{array}\)
Câu 55:
Ta có:
\(\begin{array}{l}
32x_1^2 + 18x_2^2 = 1152\\
\Rightarrow {\left( {\dfrac{{{x_1}}}{6}} \right)^2} + {\left( {\dfrac{{{x_2}}}{8}} \right)^2} = 1\\
\Rightarrow \left\{ \begin{array}{l}
{A_1} = 6cm\\
{A_2} = 8cm
\end{array} \right.\\
x_2^2 + \dfrac{{v_2^2}}{{{\omega ^2}}} = A_2^2\\
\Rightarrow {\omega ^2} = 12\\
{x_2} = 4\sqrt 3 cm \Rightarrow x_1^2 = 9\\
x_1^2 + \dfrac{{v_1^2}}{{{\omega ^2}}} = A_1^2 \Rightarrow {v_1} = 18cm/s\\
\end{array}\)
