Ta có:

\(A=\frac{12}{2}=6\left(\operatorname{cm}\right)\)
\(T=\frac{\Delta t}{N}=\frac{62,8}{20}=3,14\left(s_{}\right)\)
\(\omega=\frac{2\pi}{T}=\frac{2\pi}{3,14}\thickapprox2\left(\frac{rad}{s}\right)\)
\(\left\vert v\right\vert=\omega\sqrt{A^2-x^2}=2.\sqrt{6^2-\left(-2\right)^2}=8\sqrt2\left(\frac{\operatorname{cm}}{s}\right)\)
Lại có: \(a=-\omega^2x=-\left(2\right)^2.\left(-2\right)=8\left(\frac{\operatorname{cm}}{s^2}\right)\)

Ta có:

\(\omega=\frac{2\pi}{T}=\frac{2\pi}{4}=\frac12\pi\)

\(\frac{t}{T}=\frac32\Rightarrow t=\frac32T=T+\frac{T}{2}\Rightarrow S=4A+2A=48\Rightarrow A=8\operatorname{cm}\)

\(\varphi0=\frac{\pi}{2}\)

\(\Rightarrow x=8\cos\left(\frac12\pi t+\frac12\pi\right)\left(\operatorname{cm}\right)\)