Question

Answer 1

\(v\left(t\right)=x'\left(t\right)=-2\pi.sin\left(\pi t-\dfrac{\pi}{3}\right)\)

\(v\left(t\right)=0\Rightarrow-2\pi.sin\left(\pi t-\dfrac{\pi}{3}\right)=0\)

\(\Rightarrow sin\left(\pi t-\dfrac{\pi}{3}\right)=0\)

\(\Rightarrow\pi t-\dfrac{\pi}{3}=k\pi\)

\(\Rightarrow t=k+\dfrac{1}{3}\) với \(k\in Z\)