00:01
So for this question, we need to find the rotational kinetic energy after six revolutions.
00:07
So we have a hollow spherical shell.
00:17
We have a mass of 8 .20 kilograms.
00:22
We have a radius of 0 .220 meters.
00:28
An initial angular velocity of zero radiance per second.
00:34
Our angular acceleration alpha is 0 .890 radiance per second squared.
00:43
And then delta theta would be six revolutions or 12 pi radians.
00:55
And for a hollow spherical shell, the moment of inertia i will be 2mr squared over 3.
01:04
So at this point we can say, okay, the kinetic energy, the rotational kinetic energy is going to be equal to half i omega squared.
01:18
And we can substitute for i and say it's going to be mr squared omega squared over three.
01:30
Again, this factor of one over two cancels out this factor of two here.
01:35
So we only have a factor of 1 over 3.
01:38
And then we can use angular kinematics, essentially, to find the final angular velocity...