Bài 2.
\(x=-10cos\left(\pi t+\dfrac{2\pi}{3}\right)\)
\(a=-\omega^2Acos\left(\omega t+\varphi\right)=-\pi^2\cdot-10cos\left(\pi t+\dfrac{2\pi}{3}\right)=10\pi^2cos\left(\pi t+\dfrac{2\pi}{3}\right)\)
a)\(A=-10;T=\dfrac{2\pi}{\omega}=\dfrac{2\pi}{\pi}=2s;\omega=\pi;f=\dfrac{1}{T}=\dfrac{1}{2}=0,5Hz;\varphi_0=\dfrac{2\pi}{3}\)
b)Tại \(t=3s\Rightarrow a=10\pi^2cos\left(\pi\cdot3+\dfrac{2\pi}{3}\right)=49,34\)m/s2
c)Tại \(x=-5\sqrt{2}cm\Rightarrow a=-\omega^2x=-\pi^2\cdot\left(-5\sqrt{2}\right)=5\sqrt{2}\pi^2\)m/s2
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