Question

A disk with a rotational inertia..

Answer 1

\[\tau = \dfrac{dL}{dt} \implies L = \int \tau\, dt\]

simply integrate the torque

Answer 2

\[L(3)-L(1) = \int\limits_1^3 \tau \,dt \]
\[L(3)-5.11 = \int\limits_1^3 5.28+9.83t\,dt \]

you can solve \(L(3)\)