\(x=0.4\)
So, final \(\mathrm{KE}\) is zero as it stops, so work will be Initial \(L=K . E=\frac{1}{2} I \omega^{2}\)
as,
\(\omega=2 \pi f\)
\(f=10 r e v / s e c\)
\(\omega=20 x \rightarrow 62.8\)
\(I=\frac{M R^{2}}{2}=0.08\)
so, work done \(=\frac{1}{2} \times 0.08 \times(62.8)^{2}\)
\(158\, J\)