$x=5 \cos (2 \pi t+\pi / 4)$
$t=\frac{3}{2} s$
$x=5 \cos (3 \pi+\pi / 4)$
$x=5 \cos \left(\frac{13 \pi}{4}\right)$
$x=-5 \cos \frac{\pi}{4}$
$x=-\frac{5}{\sqrt{2}}$
Acceleration
$a=-\omega^2 x$
$a=-4 \pi^2 x-\frac{5}{\sqrt{2}}$
$a=139.56 \,m / s ^2$
$(a)$ Potential energy is always equal to its $K.E.$
$(b)$ Average potential and kinetic energy over any given time interval are always equal.
$(c)$ Sum of the kinetic and potential energy at any point of time is constant.
$(d)$ Average $K.E.$ in one time period is equal to average potential energy in one time period.
Choose the most appropriate option from the options given below:
