A circular grindstone with a rotational inertia of \(I = 0.50 \text{ kg}\cdot\text{m}^2\) is rotating freely at an initial angular speed of \(\omega_i = 12 \text{ rad/s}\). A tool is pressed against the outer rim of the grindstone, exerting a constant opposing frictional torque of magnitude \(\tau = 2.0 \text{ N}\cdot\text{m}\). What is the rotational kinetic energy of the grindstone after it has rotated through an angular displacement of \(\Delta\theta = 8.0 \text{ rad}\)?