a) Wt​=21​mω2x2=21​mω2.(2A​)2=41​W=41​.0,16=0,04 J

Wđ​=W−Wt​=0,16−0,04=0,12 J

b)Wt​=2W​⇒21​mω2x2=21​.21​mω2A2

\(\Rightarrow x = \pm \frac{A}{\sqrt{2}} .\)

a) PTVT : v = 4cos(πt−2π​+2π​) = 4cos(πt) (cm/s)

b) PTGT : a= \(\pi^2\) . \(\frac{4}{\pi}\) cos(πt − \(\frac{\pi}{2}\) +π) = 4πcos(πt+\(\frac{\pi}{2}\) ​) (cm/s²)

a)x \(= 5 sin ⁡ \left(\right. 2 \pi . 5 + \frac{\pi}{6} \left.\right) = 2 , 5\) cm

v = 10πcos(2π.5 + 6π​) = 5\(\sqrt{30}\) cm/s

a = −\(\omega^2\) x = −(2π\()^2\) . 2,5 =−100 cm/s²

^b)x = 5 sin\(120^{o}\) =2,5\(\sqrt3\)  cm

\(v = 10 \pi cos ⁡ 12 0^{o} = - 5 \pi\) cm/s

\(a = - \omega^{2} x = - 4 \pi^{2} . 2 , 5 \sqrt{3} = - \sqrt{3}\) cm/s²

v = \(\omega\sqrt{A^2-x^2}\) = \(2\sqrt{6^2-\left(-2\right)^2}\) = 8\(\sqrt2\) (cm/s)

a = -\(\omega^2x\) = -\(2^2\) .(-2) = 8 (\(\operatorname{cm}\)/\(s^2\) )

x = 8 cos(\(\frac{\pi}{2}t+\frac{\pi}{2}\) )