
$T = mg + \frac{{m{v^2}}}{r} = mg + mv\omega $ ( $v = r\omega$)
putting $v = \sqrt {2gh} $ and $\omega= \frac{{2\pi }}{T} = \frac{{2\pi }}{2} = \pi $
we get $T = m\;(g + \pi \sqrt {2gh} )$
$y = \frac{1}{{\sqrt a }}\,\sin \,\omega t \pm \frac{1}{{\sqrt b }}\,\cos \,\omega t$ will be

$(A)$ The force is zero $t=\frac{3 T}{4}$
$(B)$ The acceleration is maximum at $t=T$
$(C)$ The speed is maximum at $t =\frac{ T }{4}$
$(D)$ The $P.E.$ is equal to $K.E.$ of the oscillation at $t=\frac{T}{2}$
