Answer
$T=12s$
Work Step by Step
We know that
$T=2\pi\sqrt\frac{I}{K}$................ eq(1)
Also,
$K=\frac{T}{\theta}=\frac{0.20}{0.85}=0.235\frac{N.m}{rad}$
and $I=\frac{2}{5}mR^2$
Thus, after substituting these in equation(1), the equation (1) becomes
$T=2\pi\sqrt\frac{\frac{2}{5}mR^2}{K}$
We plug in the known values to obtain:
$T=2(3.1416)\sqrt\frac{\frac{2}{5}(95)(0.15)^2}{0.235}$
$T=12s$
