Answer:
[tex]5*10^{5} Joule[/tex]
Explanation:
Total rotational kinetic energy =[tex]\frac{1}{2}*Inertia(angular speed)^{2}[/tex]
(Here fly wheel may have translational kinetic energy but we ignore here)
Angular speed = 3000 revolutions per minute
Angular speed =[tex]\frac{3000}{60}=50[/tex] revolutions per second
Thus , Kinetic energy =[tex]\frac{1}{2}*400\frac{3000}{60} ^{2}[/tex]
= [tex]5*10^{5} Joule[/tex]