Answer:
New moment of inertia will be [tex]I=1.92kgm^2[/tex]
Explanation:
It is given initially angular velocity [tex]\omega =6rev/sec=6\times 2\pi =37.68rad/sec[/tex]
Moment of inertia [tex]I=0.4kgm^2[/tex]
Angular momentum is equal to [tex]L=I\omega =37.68\times 0.4=15.072kgm^2/sec[/tex]
Now angular velocity is decreases to [tex]\omega =1.25rev/sec=1.25\times 2\times 3.14=7.85rad/sec[/tex]
As we know that angular momentum is conserved
So [tex]15.072=I\times 7.85[/tex]
[tex]I=1.92kgm^2[/tex]
So new moment of inertia will be [tex]I=1.92kgm^2[/tex]