
$I_{\text {support }}=m R^{2}+m R^{2}=2 m R^{2}$
$T=2 \pi \sqrt{\frac{\left(2 m R^{2}\right)}{m g R}} =2 \pi \sqrt{\frac{2 R}{g}}$
$\Rightarrow R=\frac{T^{2} g}{8 \pi^{2}}$
A seconds pendulum is a pendulum whose period is precisely $two\, seconds; one \,second$ for a swing in one direction and $one\, second$ for the return swing. Ie. $T=2 \varepsilon,$ so we have
$R=\frac{2^{2} \times \pi^{2}}{8 \pi^{2}}=0.5 \mathrm{m}$
$y_1 = \sin \left( {\omega t + \frac{\pi }{3}} \right)$ and $y_2 = \sin \omega t$ is :

Simultaneously at $t=0$, a small pebble is projected with speed $v$ from point $P$ at an angle of $45^{\circ}$ as shown in the figure. Point $P$ is at a horizontal distance of $10 \ cm$ from $O$. If the pebble hits the block at $t=1 \ s$, the value of $v$ is (take $g =10 \ m / s ^2$ )