Find time after which to the energy will become half of initial maximum value in damped force oscillation.
$\frac{1}{\sqrt{2}}=e^{-b t / m}$
$\ln \sqrt{2}=\frac{b t}{m}$
$t=\frac{m}{b} \times \frac{1}{2} \ln 2$

$\vec r = (\sin \,t\,\hat i\, + \,\cos \,t\,\hat j\, + \,t\,\hat k)m$
Find time $'t'$ when position vector and acceleration vector are perpendicular to each other
$(A)$ $E_1 \omega_1=E_2 \omega_2$ $(B)$ $\frac{\omega_2}{\omega_1}=n^2$ $(C)$ $\omega_1 \omega_2= n ^2$ $(D)$ $\frac{E_1}{\omega_1}=\frac{E_2}{\omega_2}$

${x}_{1}=5 \sin \left(2 \pi {t}+\frac{\pi}{4}\right)$ and ${x}_{2}=5 \sqrt{2}(\sin 2 \pi {t}+\cos 2 \pi {t})$
The amplitude of second motion is ....... times the amplitude in first motion.