\(Acos\left(\dfrac{2\pi}{T}t+\varphi\right)=5\)

\(\left|-A\omega\sin\left(\dfrac{2\pi}{T}t+\dfrac{\pi}{2}+\varphi\right)\right|=50\)

\(sin\left(\dfrac{2\pi}{T}t+\dfrac{\pi}{2}+\varphi\right)=cos\left(\dfrac{2\pi}{T}t+\dfrac{\pi}{2}+\varphi-\dfrac{\pi}{2}\right)=cos\left(\dfrac{2\pi}{T}t+\varphi\right)\)

\(\omega=10\)\(m=\dfrac{k}{\omega^2}=1\)