$ \Rightarrow {g_P} = \frac{{2\,h}}{{{t^2}}} = \frac{{2 \times 8}}{4} = 4\,m/{s^2}$
Using $T = 2\pi \sqrt {\frac{l}{g}} $ ==> $T = 2\,\pi \sqrt {\frac{1}{4}} = \pi = 3.14\,$sec.
$(A)$ 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 $t=\frac{T}{2}$
Then the values of $A$ (in $m$) and $T$ (in $sec$) are :
