Two discs of same moment of inertia rotating about
their regular axis passing through centre and
perpendicular to the plane of disc with angular
velocities $\omega_1$ and $\omega_2$. They are brought into contacl
face to face coinciding the axis of rotation. The
expression for loss of energy during this process is - Clay6.com, a Free resource for your JEE, AIPMT and Board Exam preparation

Two discs of same moment of inertia rotating about
their regular axis passing through centre and
perpendicular to the plane of disc with angular
velocities $\omega_1$ and $\omega_2$. They are brought into contacl
face to face coinciding the axis of rotation. The
expression for loss of energy during this process is

$\begin{array}{1 1} (1) \frac{1}{2} I (\omega_1+\omega_2)^2 \\ (2) \frac{1}{4} I (\omega_1-\omega_2)^2 \\ (3) I (\omega_1+\omega_2)^2 \\ (4) \frac{1}{8} (\omega_1-\omega_2)^2 \end{array} $