<p>Two discs of moment of inertia&nbsp;<span class="equation">\(I_1 = 4kgm^2\)</span>&nbsp;and&nbsp;<span class="equation">\(I_2=2kgm^2\)</span>&nbsp;, about their central axes &amp; normal to their planes, rotating with angular speeds 10 rad/s&nbsp; &amp; 4 rad/s&nbsp; respectively are brought into contact face to face with their axes of rotation coincident. The loss in kinetic energy of the system in the process is _________ J</p>